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关于唐朝历史文化的小学生英语作文全文共3篇示例，供读者参考篇1The Tang Dynasty, also known as the Golden Age of Chinese civilization, was a time of great prosperity and advancements in art, culture, and technology. It is often considered one of the most glorious periods in Chinese history.The Tang Dynasty was founded in 618 AD by Emperor Gaozu, who was a brilliant military leader. During his reign, the empire expanded its territory and the Silk Road flourished, bringing trade and cultural exchange with other civilizations.One of the most famous emperors of the Tang Dynasty was Emperor Taizong, who is praised for his wise governance and military prowess. He encouraged learning and scholarship, setting up the imperial examination system to select talented officials based on their knowledge of Confucian classics.The Tang Dynasty was a time of great cultural flourishing, with poetry, painting, calligraphy, and music reaching new heights. Tang poets such as Li Bai and Du Fu are still renownedfor their lyrical and expressive verses. Tang artists also excelled in creating exquisite silk paintings and porcelain ceramics.Buddhism played a significant role in Tang culture, with monasteries and temples flourishing across the empire. The famous Giant Wild Goose Pagoda in Xi'an was built to house Buddhist scriptures brought from India by the monk Xuanzang.In terms of technology, the Tang Dynasty made significant advancements in engineering, with the construction of the Grand Canal linking the Yangtze and Yellow Rivers, facilitating trade and transportation. The Tang also developed sophisticated iron smelting techniques and were known for their intricate bronze sculptures.The Tang Dynasty was also a time of cosmopolitanism, with foreigners from Central Asia, India, and Persia coming to China to trade and share their knowledge. This cultural exchange enriched Chinese society and contributed to the flourishing of arts and sciences.Unfortunately, the Tang Dynasty eventually declined due to internal rebellions and external invasions, leading to the collapse of the empire in 907 AD. Despite its fall, the legacy of the Tang Dynasty lives on in Chinese literature, art, and culture, and continues to inspire generations of artists and scholars.In conclusion, the Tang Dynasty was a period of great cultural achievement and technological advancement in Chinese history. Its legacy continues to shape Chinese culture and society to this day, making it a vital part of China's rich historical heritage.篇2The Tang Dynasty is often regarded as a golden age in Chinese history, known for its flourishing cultural and artistic achievements. As a primary school student, I have learned a lot about the history and culture of the Tang Dynasty, and I would like to share some of the interesting facts I have discovered.During the Tang Dynasty, China experienced a period of great prosperity and innovation. The empire was ruled by a series of capable emperors who promoted trade, diplomacy, and the arts. One of the most famous emperors of the Tang Dynasty was Emperor Taizong, who is remembered for his military conquests and his promotion of Confucianism. Another notable figure from this period is Empress Wu Zetian, who became the only female emperor in Chinese history.The Tang Dynasty was also known for its advancements in science and technology. The Chinese invented paper moneyduring this time, which revolutionized commerce and trade. They also made significant progress in fields such as agriculture, irrigation, and astronomy. The construction of the Grand Canal, a massive waterway that connected the Yellow River and the Yangtze River, was a major achievement of the Tang Dynasty.In terms of culture, the Tang Dynasty was a time of great creativity and artistic achievement. The dynasty produced some of the greatest poets, painters, and musicians in Chinese history. Li Bai and Du Fu are two of the most famous poets from this period, known for their lyrical and emotional verse. Tang Dynasty painters were known for their realistic portrayals of landscapes and daily life, while Tang Dynasty musicians created beautiful melodies that are still enjoyed today.The Tang Dynasty was also a time of religious diversity, with Buddhism, Daoism, and Confucianism coexisting peacefully. Many Buddhist temples and monasteries were built during this period, and Buddhism became a major influence on Tang Dynasty art and culture. The famous Giant Wild Goose Pagoda in Xi'an, built to house Buddhist scriptures brought back from India, is a lasting symbol of the influence of Buddhism on the Tang Dynasty.Overall, the Tang Dynasty was a period of great achievement and cultural richness in Chinese history. As a primary school student, I have enjoyed learning about this fascinating period and exploring its art, literature, and history. The legacy of the Tang Dynasty continues to inspire and captivate people around the world, and I am grateful for the opportunity to study and appreciate this remarkable era.篇3The Tang Dynasty, also known as the Golden Age of Chinese history, lasted from 618 to 907 AD. During this time, China experienced a period of economic prosperity, cultural flourishing, and military expansion. The Tang Dynasty was known for its innovation, art, and poetry, making it a significant period in Chinese history.One of the most famous rulers of the Tang Dynasty was Emperor Taizong. He was known for his military conquests and his wise leadership. Under his rule, China expanded its territory and became one of the most powerful empires in the world. Emperor Taizong also promoted the arts and literature, leading to a golden age of culture in China.Another important figure from the Tang Dynasty was Li Bai, a famous poet. His poems are still read and studied today, and he is considered one of the greatest poets in Chinese history. Li Bai's poems often reflect the beauty of nature and the joys and sorrows of life. His poetry is celebrated for its emotional depth and lyrical beauty.The Tang Dynasty was also a time of great innovation in China. The invention of woodblock printing revolutionized the way books were produced and distributed, making literature more accessible to the general population. The Tang Dynasty also saw advancements in agriculture, technology, and trade, leading to a period of economic prosperity for China.In addition to its cultural and technological achievements, the Tang Dynasty was known for its religious tolerance and cosmopolitanism. Buddhism flourished during this time, and many Buddhist temples and statues were built throughout China. The Tang Dynasty also had diplomatic relations with many other countries, leading to cultural exchanges and the spread of ideas and technologies.Overall, the Tang Dynasty was a period of great achievement and progress in Chinese history. Its cultural, artistic, and technological achievements continue to be celebrated andstudied today. The legacy of the Tang Dynasty lives on in Chinese literature, art, and culture, making it a key period in the history of China.。
As a high school student with a passion for the performing arts, I have always been captivated by the magic of a wellprepared performance. Its not just about the final act that mesmerizes the audience, but the journey leading up to it, filled with hard work, dedication, and a touch of creativity.My most memorable experience was preparing for the schools annual talent show. It was an opportunity to showcase my skills and share my love for the stage with the entire school. The theme for the show was A Night of Stars, and I knew I had to come up with something that would not only entertain but also inspire.I decided to perform a monologue from one of my favorite plays, Hamlet. The challenge was to bring the character to life and make the audience feel the depth of his emotions. I spent countless hours studying the script, understanding the context, and practicing the delivery. Every line had to be perfect, every pause meaningful.The process of preparation was intense but exhilarating. I would rehearse in front of the mirror, trying to capture the essence of the character. I would record my performances and watch them back, analyzing every gesture, every facial expression. I wanted to ensure that my portrayal was authentic and resonated with the audience.As the day of the performance approached, the anticipation grew. I could feel the excitement and nervousness building up. I knew that all the hard work would culminate in a few minutes on stage, and I had to make it count.The moment finally arrived, and I stepped onto the stage with a mix of emotions. The spotlight was on me, and I could hear the silence of the auditorium. I took a deep breath, and as I began my monologue, I felt a surge of energy. The words flowed effortlessly, and I could see the audiences reactions the gasps, the smiles, the tears. It was a moment of pure connection, and I knew that all the preparation had paid off.The applause at the end of my performance was deafening. It was a validation of my efforts and a testament to the power of a wellprepared performance. The feedback I received was overwhelmingly positive, with many expressing how moved they were by my portrayal.This experience taught me the importance of dedication and the impact of a wellexecuted performance. Its not just about the applause or the accolades its about the journey and the growth that comes with it. Its about the ability to touch peoples hearts and minds through the power of art.In conclusion, a wellprepared performance is a beautiful blend of hard work, creativity, and passion. Its a journey that requires commitment, but the rewards are immeasurable. As I continue to pursue my love for the performing arts, I carry with me the lessons learned from this experience to always strive for excellence, to connect with the audience, and to make every performance count.。
2020秋国家开放大学“开放本科”行管专业《管理英语4》期末考试真题7试题与答案一、交际用语：5小题，每小题2分，共10分。
题目1—Scott，I'd like to have your opinions about my written report.—C_ But I have one suggestion.选择一项：A. That's a good idea.B. You are too modest.C. It looks fine to me.题目2— Haven't seen you for ages. What are you busy doing now?— C_选择一项：A. Yes ,long time no see.B. Yeah, thanks for coming.C. I am working part time in a bookstore.题目3— Wow! This is a fantastic project! I've never known you're so creative.— C__选择一项：A. Don't mention it.B. Great, I dare to say I am a talent.C. Thanks for your compliments.题目4— I think things have been a bit difficult for us the last couple of months.—_A_. We've been working hard, but still getting behind.选择一项：A. You're rightB. I'm afraidC. I don’t think so题目5—This project is too big for me to finish on time. —_C_.选择一项：A. Please do me a favorB. That is a daydreamC. I'll give you a hand二、词汇语法：15小题，每小题2分，共30分。
Performance Evaluation in the WorkplacePerformance evaluation is a crucial aspect of any organization, as it not only gauges the productivity of employees but also helps in aligning individual goals with the overall objectives of the company. In this assignment, we will explore the various facets of performance evaluation, its importance, and how it can be effectively implemented in the workplace.Performance evaluation is a process that assesses the degree to which an employee has met the expectations set out in their job description. It typically involves objective measures of an employee's work, such as the quantity and quality of their output, as well as subjective measures, such as their attitude, professionalism, and teamwork.The importance of performance evaluation cannot be understated. Firstly, it provides a clear understanding of an employee's strengths and areas for improvement. This information can then be used to develop training programs or provide guidance on how to improve specific skills or behaviors. Secondly, it acts as a motivator for employees to work harder and excel in their respective roles. By knowing that their performance is being evaluated, employees are more likely to put in extra effort to achieve better results. Finally, it also helps in maintaining a high standard of work ethics and professionalism within the organization.To ensure that performance evaluation is conducted effectively, several key factors need to be considered. Firstly, clear and SMART (Specific, Measurable, Achievable, Relevant, Time-bound) goals should be set for each employee. These goals act as a roadmap for employees to guide their work and measure their progress. Secondly, regular feedback and supervision are essential. Employees should be appraised on a regular basis and provided with constructive criticism on their performance. This feedback should be given in a timely manner to allow for any necessary adjustments or improvements.Moreover, performance evaluation should be conducted fairly and objectively. Biases and subjective opinions should be minimized by using objective criteria and reliable assessment methods. To ensure transparency, the evaluation process should be well-documented and communicated clearly to employees. They should be informed about the evaluation criteria, how their performance will be measured, and how the evaluation will be used to inform decisions about their future within the organization.In conclusion, performance evaluation is a critical component of organizational success. It not only helps in assessing individual performance but also acts as a tool for development, motivation, and maintaining high standards of work ethics. By implementing fair, objective, and well-communicated evaluation processes, organizationscan ensure that their employees are performing at their best and aligning their efforts with the overall objectives of the company.。
对于小区里有流浪猫的看法的高中英语作文Flowing through the streets, meowing for food, and seeking warmth, stray cats are a common sight in many residential areas.对于流浪猫的存在,不同的人们有不同的看法。
有些人喜欢它们作为宠物,有些人觉得它们是城市的一种精神图腾,而还有一些人则视它们为环境污染的来源。
在这些不同的观点中,如何看待小区里的流浪猫的深度问题成为了一个值得思考的话题。
From a humanitarian perspective, many people believe that stray cats deserve our compassion and support.人道主义的角度来看,许多人认为流浪猫应该得到我们的同情和支持。
They are innocent creatures who struggle to survive in a hostile urban environment. 它们是无辜的生灵,在充满敌意的城市环境中挣扎求生。
These animals did not choose this way of life, yet they have to endure hunger, loneliness, and the risk of accidents or disease. 这些动物没有选择这种生活方式,但它们必须忍受饥饿、孤独和意外或疾病的风险。
It is our responsibility as residents of the community to provide aid and protection to these vulnerable felines. 作为社区的居民,我们有责任为这些弱势的猫提供援助和保护。
By showing kindness to stray cats, we can contribute to creating a morecompassionate and caring society. 通过对流浪猫表现出善良,我们可以有助于创造一个更有同情心和关爱的社会。
发展与文化传承结合的唯美句子1.传承千年的文化是我们发展的源泉。
The thousand-year-old culture is the source of our development.2.唯有传承文化，才能传播美的力量。
Only by inheriting culture can we spread the power of beauty.3.文化传承是一座连接过去与未来的桥梁。
Cultural inheritance is a bridge connecting the past and the future.4.在发展的道路上，不应忘记传统文化的珍贵。
On the path of development, we should not forget the preciousness of traditional culture.5.传承优秀的文化是对历史的尊重。
Inheriting excellent culture is a respect for history.6.文化传承是一种使命，是一种责任。
Cultural inheritance is a mission and a responsibility.7.我们要用发展的力量让文化得以传承。
We should use the power of development to inherit culture.8.传承文化，是对先人的敬仰和感恩。
Inheriting culture is a respect and gratitude to our ancestors.9.在现代社会中，我们需要保护和传承传统文化。
In modern society, we need to protect and inherit traditional culture.10.传统文化中蕴含着发展的智慧。
Traditional culture contains the wisdom of development.11.文化传承的重要性不可忽视。
一、阅读理解1. 请阅读下面短文，并根据所读内容在文章后表格中的空格里填入一个最恰当的单词。
注意：请将答案写在答题卡上相应题号的横线上。
每个空格只填一个单词。
T he Art of Chinese CalligraphyChinese calligraphy is the world’s most favorable form of art. When 1 was a preschooler, I was briefly taught by my grandfather to write Chinese calligraphy. Even though everything has gradually been only a blur (模糊) in my memory over the years, one thing I certainly have not lost is that I can still grip the ink brush correctly.Imagine that someone obtains such a cherished occasion to sit down and spend a little unaccompanied time of quietness, allowing one's intellect to think freely and express out in a written script their deepest thoughts.A piece of Xuan paper is first carefully placed on top of a desk pad. Then, use a paper- weight to hold down the Xuan paper, so it will be alwayslocked in the right spot. Next without any hesitation, reach for the best ink brush. Do remember to immerse (浸润) the brush with just enough ink so there won't be any ink dripping. Then start to write. While the mind unfolds, the brush sheer per stokes of Chinese character into the rhythmic motion of expressions,In history, Chinese calligraphers have always written the script as a common way for message transmission during various audience engagements of contributors. It also makes for better cultural understanding of a different period of Chinese history. Chinese calligraphers have a variety of reasons to study the art form. For some people. practicing writing the regular script will keep the traditional culture alive. Others think it a perfect way to relax from all the daily happenings. There's still an uncountable new form of script style that has kept the art going in a way to promote the fine art of Chinese culture in our present day.Nowadays, Chinese calligraphers strongly believe there's more than just written communication. Countless existing works display Chinese literature. They understand what it meant to become an accomplished Chinese calligrapher. It takes many years of strictly copying from the master's correct written stokes, to gain the skill in the regular script until exemplary, perfect and beyond expert level. One requirement is to know the wring structures of several Chinese script styles.The new approach to script writing is gaining ground, especially in western countries. Inspiring Chinese calligraphers who are willing to perfect the craft tend to create new ideas to re- present the visible images. The contemporary bending of color hypothesis sets a brand-new standard for Chinese calligraphers. That makes every sort of collective portrait of Chinese characters into a well- presented masterwork of applied arts.As much exceptional quality of diverse formed of masterpiece appears overtime. It's a reminder that in all classes of society we must pass our heritage down to the next generation so our ancestors are more than merely just a portion of history. Instead, it is never to be forgot- ten as an integral part of the culture. “A soul is essential for a country and a nation, " Chinese President Xi Jinping said. “Professionals in the sectors of culture, art, philosophy and social sciences are important soul builders.”2. 请认真阅读下列短文，并根据所读内容在文章后表格中的空格里填入一个最恰当的单词。
2024年牛津译林版英语高一上学期期末复习试卷及解答参考一、听力第一节（本大题有5小题，每小题1.5分，共7.5分）1、You will hear a short conversation. Choose the best answer to the question you hear. [音频]A)The restaurant is across from the post office.B)The post office is on the left or the right of the bus stop.C)The post office is down the street.D)The restaurant is down the street.答案：A解析：In the conversation, the speaker says, “It’s across from the post office.” This indicates that the restaurant is di rectly opposite the post office, so the correct answer is A.2、Listen to another conversation and choose the best answer to the question. [音频]A)The speakers are neighbors.B)The speakers are old classmates.C)The speakers are brother and sister.D)The speakers are librarian and reader.答案：B解析：In the conversation, one person mentions, “Did you go to school with Tom?” This suggests that the speakers might have been classmates. Therefore, the correct answer is B.3、You hear a conversation between two students discussing their science fair projects.Student A: “How’s your science fair project going?”Student B: “Not too bad. I’m working on a project about renewable energy.”Question: What is Student B’s project about?A. Chemistry experimentsB. Renewable energyC. Botany researchD. Physics simulationsAnswer: B. Renewable energyExplanation: The second student explicitly mentions that they are working ona project about renewable energy.4、You listen to a short lecture about the importance of water conservation.pro fessor: “Water is a vital resource for all living things, and unfortunately, it’s being wasted at an alarming rate. According to recent studies, up to 60% of the water used in homes is wasted due to leaks and inefficient fixtures.”Question: According to the professor, what is one major cause of water waste at homes?A. Outdoor wateringB. Improper disposal of hazardous materialsC. Leaks and inefficient fixturesD. Excessive showeringAnswer: C. Leaks and inefficient fixturesExplanation: The professor directly states that up to 60% of water used in homes is wasted due to leaks and inefficient fixtures.5、Listen to the following dialogue and choose the best answer to the question.A. The man has finished his homework.B. The woman is helping the man with his homework.C. The man is waiting for the woman to finish her homework.D. The man and the woman are going to the library together.Answer: BExplanation: The woman says, “You know, I have a lot of homework to do. Would you li ke to help me?” This indicates that she is asking the man for help with his homework. Therefore, the correct answer is B, “The woman is helping the man with his homework.”二、听力第二节（本大题有15小题，每小题1.5分，共22.5分）1、How many people are having the conversation?A) 2B) 3C) 4Answer: BExplanation: The conversation is between a student and two teachers, making a total of three people.2、What will the man do?A) Write a letterB) Make a listC) Draw a mapAnswer: AExplanation: The man mentions that he will write a letter, indicating that he will be writing some text.3、Questions: Listen to the dialogue and select the best answer for each question.A. The man is planning to go to a party this evening.B. The woman is inviting the man to have dinner.C. The man is inviting the woman to a party he is attending.D. The woman is declining the invitation to the party.Answer: CExplanation: The woman says, “I heard you’re going to a party this evening, are you?” indicating that she is aware of the man’s party plans and is ex tending an invitation to accompany him. The man answers, “Yes, and you’re welcome to join us,” confirming the invitation. Thus, the correct answer is C.4、Questions: Listen to the conversation and choose the most appropriate response for the following statement.Woman: “That’s amazing! How did you manage to learn Italian in such a short time?”Man: “I started studying it every day after work.”A. She is impressed by his language skills.B. She is comparing him to someone else.C. She is questioning hisitese weather.D. She is asking for help learning Italian.Answer: AExplanation: The woman’s use of the phrase “That’s amazing!” suggests that she is express ing admiration or surprise about the man’s achievement in learning Italian. Therefore, the correct response to her statement is that she is impressed by his language skills, which is option A.5.You are going to listen to a conversation between two students about their summer vacation plans. Listen carefully and choose the best answer to each question.Question 5: What activity does the girl NOT want to do this summer?A. Go to the beachB. Visit her grandparentsC. Take a language courseD. Go hikingAnswer: DExplanation: The girl mentions that she doesn’t want to go hiking because she is not interested in it. She enjoys the beach, visiting her grandparents, and taking a language course.6.Listen again to part of the conversation. The girl explains why she is interested in taking a language course. Choose the correct reason from the following options.Question 6: Why is the girl interested in taking a language course this summer?A. She wants to improve her grades in schoolB. She has always wanted to learn a new languageC. She needs to study for a standardized testD. She wants to practice her speaking skillsAnswer: BExplanation: The girl states that she has always wanted to learn a new language, which is why she is interested in taking a language course. The other options are not mentioned in the conversation.7、 Traffic jam. (答案：7、A)解析：The dialogue mentions the woman saying “The traffic is terrible,” which indicates there is a traffic jam. Therefore, the answer is A (Traffic jam).8、 A listening conference will be held the day after tomorrow. (答案：8、C)解析：The dialogue mentions the man saying “The next listening conference will be held the day after tomorrow,” which indicates the conference wi ll take place two days from now. Therefore, the answer is C (A listening conference will be held the day after tomorrow).9.You will hear a conversation between two friends discussing their weekend plans. Listen carefully and choose the best answer to the question.Question: What does the man plan to do during the weekend?A. Go hiking in the mountains.B. Visit an art gallery.C. Take a dance class.D. Attend a sports event.Answer: CReason: The man mentions that he has signed up for a dance class and can’t miss the practice on Saturday, which indicates his plan for the weekend.10.You will hear a short passage about the importance of environmental conservation. Listen carefully and answer the following question.Question: What is the main purpose of the passage?A. To encourage listeners to participate in a local beach cleanup.B. To compare different methods of recycling.C. To explain how environmental conservation benefits the economy.D. To describe the effects of pollution on wildlife.Answer: CReason: The passage emphasizes the economic benefits of environmental conservation, such as the creation of green jobs and the preservation of natural resources, making option C the most accurate answer.11.Question: What does the woman mean when she says “I’m not surprised at all”?A) She’s very surprised.B) She’s a little surprised.C) She’s not at all surprised.D) She’s a bit surprised.Answer: C) She’s not at all surprised.Explanation: The woman’s response indicates that she expected the result or situation, thus she is not surprised at all.12.Question: Why does the man decide to visit the art gallery this weekend?A) Because he is interested in art.B) Because he wants to meet his friend.C) Because he needs to finish some work.D) Because it is his friend’s birthday.Answer: A) Because he is interested in art.Explanation: The man mentions that he has always been interested in art, and that he has heard good things about the art gallery, indicating his reason for visiting is due to his interest in art.13、听下面的对话，从题后所给的选项中选出最佳选项。
英语作文东西方文化交流The world has always been a diverse and interconnected place, with different cultures and civilizations coexisting and influencing one another. The exchange of ideas, traditions, and practices between the East and West has been a significant part of this global interaction, shaping the development of human societies throughout history.One of the most notable examples of cultural exchange between the East and West is the Silk Road, a vast network of trade routes that connected China to the Mediterranean region. Along these routes, goods, technologies, and cultural elements were exchanged, facilitating the spread of ideas and the cross-pollination of traditions. The introduction of Chinese inventions, such as paper, the compass, and gunpowder, to the West had a profound impact on the course of human history, while Western innovations, such as glassmaking and metallurgy, were in turn adopted by Eastern civilizations.Beyond the realm of material goods, the exchange of knowledge and philosophical ideas has been a crucial aspect of the cultural dialogue between the East and West. The ancient Greek philosophers, such asPlato and Aristotle, had a significant influence on the development of Eastern thought, with their ideas being incorporated into the philosophical traditions of China, India, and the Middle East. Conversely, Eastern philosophies, such as Confucianism, Taoism, and Buddhism, have had a profound impact on Western thinkers, shaping the development of Western spirituality and ethics.The exchange of religious and artistic traditions has also been a crucial aspect of the cultural interaction between the East and West. The spread of Buddhism from India to China, Korea, and Japan, for example, led to the creation of magnificent works of art and architecture, such as the Mogao Caves in Dunhuang and the Terracotta Army in Xi'an. Similarly, the influence of Islamic art and architecture on European cultures can be seen in the intricate geometric patterns and calligraphic designs that adorned the buildings and artifacts of the Islamic world.In the modern era, the cultural exchange between the East and West has continued to evolve, with new forms of interaction and collaboration emerging. The globalization of media and communication technologies has facilitated the widespread dissemination of cultural products, from music and film to literature and fashion. This has led to a greater awareness and appreciation of diverse cultural traditions, as well as the emergence of hybrid forms of cultural expression that blend elements from both the East andWest.At the same time, the increased mobility of people and the growth of international trade and investment have created new avenues for cultural exchange. Immigrants and expatriates have brought their cultural traditions with them, enriching the diversity of their host societies and fostering new forms of cultural hybridity. International collaborations in fields such as science, technology, and the arts have also led to the cross-pollination of ideas and the creation of innovative solutions to global challenges.Despite the many benefits of cultural exchange, it is important to recognize that the interaction between the East and West has not always been a harmonious one. Colonialism, imperialism, and the imposition of Western values and institutions on Eastern societies have often led to the suppression or destruction of indigenous cultures. The legacy of this historical imbalance continues to shape the dynamics of cultural exchange, with ongoing debates and tensions surrounding issues of cultural appropriation, representation, and power dynamics.To address these challenges, it is crucial that the cultural exchange between the East and West be grounded in principles of mutual respect, understanding, and collaboration. This requires a deep engagement with the histories, traditions, and perspectives ofdiverse cultures, as well as a willingness to acknowledge and address the imbalances and inequities that have shaped past interactions.By fostering a more equitable and inclusive cultural exchange, we can harness the richness and diversity of human civilization to address the complex challenges facing our world. Through the sharing of knowledge, the celebration of cultural differences, and the creation of new forms of cultural expression, we can build a more interconnected and vibrant global community that celebrates the unique contributions of all its members.。
关于春天的英文演讲稿小学6篇春天的雨是连绵的、柔和的，它滋润着大地，抚摸着大地，小声地呼唤着大地，在人们不知不觉的时候，他们竟悄悄地汇成了小河，积成了深潭。
啊，原来是春雨给潭水带来绿色的生命。
一起关于春天的英文演讲稿小学6篇，欢迎查阅!关于春天的英文演讲稿1Spring is my favorite season. In spring days, everything comes out. While you are walking outside, your eyes will be filled with green.春天是我最喜欢的季节。
春天一切都发芽了。
在外面散步，眼睛里看到的都是满满的绿色。
In spring days, our world is a sunny place, which is covered with green trees and colorful flowers, so it can be described as a paradise. Especially when you are in the countryside, you can see green mountains, vast fields, clean streams, and all the living creatures, coexisting harmoniously. All of them make up the most beautiful picture in the world.在春天，我们的世界是一个充满阳光的地方，到处都覆盖着绿色的树木和色彩缤纷的鲜花，所以它可以说得上是一个天堂。
尤其是当你在乡下时，你可以看到绿色的山，广阔的田野，清澈的小溪，和所有的生物和谐共存。
所有这些组成了世界上最漂亮的画。
In spring days, the sun shines brightly, and there's also some pleasant breeze. So how charming it is while feeling the spring wind blow us. It's also wonderful to enjoy the beautiful sunshine. You will also get a lot of refreshments while having a walk outside.春天，阳光灿烂，还有一些令人愉快的微风。
On The Performance Of Coexisting Spread Spectrum SystemsOlav QuesethRadio Communication Systems, S3, Royal Institute of Technology100 44 Stockholm, Swedenolav.queseth@radio.kth.seABSTRACTWireless communication services may in the future be provided by a larger number of operators than provide the services today. A key enabling factor is the possibility to automatically share the radio spectrum. Bandwidth efficiency is defined as the number of users that can be supported by a basestation in a given spectrum. The bandwidth efficiency in a DS-CDMA and a frequency hopping system is studied when two operators share the same spectrum. The influence of base station location is also studied. The results indicate a substantial loss for the DS-CDMA system and a lower loss for the frequency hopping system.INTRODUCTIONOn the telecom market ten years into the future we expect numerous new operators as well as new services [1]. We can expect that not only the traditional mobile phone operators will provide communication services but also owners of buildings (shopping malls, railway stations, campuses etc.) or private persons may provide communication services. With more operators on the scene a problem of sharing the available radio spectrum will arise.Today a piece of spectrum is shared by means of regulation. One operator is given the exclusive use of a piece of spectrum in a specific geographical area. Various methods for giving out licenses to operators are described in [2]. When many operators share a piece of spectrum the traditional method has several drawbacks.A large number of operators create a large administrative overhead. If a resource (spectrum) is split into smaller parts the total available capacity is smaller than if the resource had not been split, this is known as trunking losses. Finally the traditional method for allocating spectrum is static in nature. A typical license may be issued for five or ten years. Markets and customer demands change more rapidly which means that the spectrum allocation rarely reflects the actual demand situation.In order to make future telecommunication systems successful we believe that these systems must be easy to deploy, i.e. they should be possible to install by the end user. Preferably no planning should be required. If planning cannot be avoided it should be possible to do by people who are not trained radio engineers. In addition future systems should require less administration from the regulatory bodies. Key factors for the success of future wireless systems are methods for automatic planning and for allowing different systems to coexist in the same spectrum. If we can find tools for allowing operators to use the same spectrum that don’t require a licensing procedure competition will be promoted. The chosen technology for a standard tends to quickly become obsolete. By avoiding standardization it becomes easier to utilise technological advances since the technology choice is not locked by a standard. Recently a number of spectrum allocations have been opened for unlicensed operation. Typically devices that operate in these must follow a set of etiquette rules that control maximum output power and how to prevent devices from consuming all available bandwidth [5]. Certain systems that don’t require a license to operate provide telephony services, e.g. DECT. The methods that allow coexistence are typically based on DCA algorithms, the performance of various DCA algorithms are studied in [3]. These generally rely on statistics to determine where there are available channels. The problem with using these algorithms for data communication is the burstiness of the traffic, which tends to make statistics unreliable.By understanding the mechanisms that underlie the behaviour of systems that operate in the same spectrum it will be easier to design methods for coexistence. In this paper we investigate the effects of using spread spectrum techniques in a shared environment. We consider both direct sequence CDMA and frequency hopping.In future systems we expect the access point locations to be less planned than today. Therefore we will also study the location influence on the properties of the shared system. Finally the amount of available spectrum influences the coexistence properties of a system and we study this influence as well.The rest of the paper outlines the system model used in our analysis. We then move on to mathematically analysing coexisting DS-CDMA systems for a special case. In order to study other cases we have performed a set of computational experiments. The paper concludes with the results and we draw some conclusions.SYSTEM MODELWe study two cellular systems that coexist in the same geographical area. Each system corresponds to one operator. In the area there are a number of users spread out that are serviced by one of the operators. We assume that all users have the same datarate.Our channel model includes distance dependent fading and a lognormal shadow fading. This model gives us a short term average C/I. Fast fading, multipath propagation etc. is ignored in these experiments since it is assumed that such channel variations are taken care of by other means, e.g. coding or diversity techniques. Mobiles and base stations are scattered over a rhombic service area and a wraparound technique is used to emulate an infinitely large system.In these experiments three different base station placement schemes have been studied.•Co-located base stations. Both operators have put their base stations at the same geographical location.•Superimposed hexagons. Each operator has his base stations arranged in a hexagonal pattern. These are shifted by half a cell size in relation to each other so that one operators base station is as far from the other operator’s basestations as possible.•Random location. The base stations are randomly located with a constant probability distribution over the service area. This models the locations of user deployed base stations.The total number of mobiles is poisson distributed. The mobiles are randomly located over the service area. Mobiles belong to one operator and do not switch. Each mobile uses the same constant datarate.Users are not handed over between operators. The reasoning behind this assumption is that we believe that the operators are reluctant to carry other operators’traffic. From a technical point of view handover may be difficult to implement since an extensive knowledge of the cells of another operator is necessary. This means that either it is necessary to perform extensive setup or have large standardized interfaces that allow the necessary information to be transferred. Finally for security reasons one operator may be reluctant to let another into their network.In this paper the analysis focuses on the downlink, i.e. the link from the fixed infrastructure to the mobile user. The reason is that in future systems we expect a lot of data going to the user. As much as 90% of the traffic may be going to the user. Thus the critical link will be the downlink even if the uplink generally is considered to be the critical one. In this paper we assume that the spreading codes used in the DS-CDMA case are perfectly orthogonal when they are from the same base station. In the frequency hopping case there is no adjacent channel interference.SHARING STRATEGIESThere are generally two ways that a piece of spectrum can be shared between two operators. Both operators can either use the whole spectrum or the spectrum can be split into two parts that are used by only one of theoperators.Figure 1 – Spectrum sharing can be done either bycoexistence in the same spectrum or by dividing thespectrum between operators.It is also possible that the spectrum can be split into smaller chunks. These chunks are then shared individually. The reason for doing that may be that the coexistence properties may be better for small systems than for large ones. However the bandwidth efficiency will be the same independent of how many chunks we study.PERFORMANCE MEASURETo evaluate the performance of the system we determine the maximum number of users that the system can handle. With handle we mean that 5% of the users in the system will not be given any service. Since the maximum number of users is a random variable we use the average as performance measure.The number of users that can be supported is determined by increasing the system load until less than 95% of the users can communicate. Each load case is an independent experiment.In the experiments where DS-CDMA is employed the power control scheme used is DCPC [4]. The C/I target used is 11 dB. If users have a C/I below 10.5 dB they are considered as unable to communicate. We run a number of DCPC iterations if there are users that have reached their maximum power one of them is randomly selected and removed. The DCPC algorithm is then run again to check if the remaining users can communicate.In the frequency hopping case all transmitters use the same power. A mobile is considered able to communicate if he has a C/I above 7 dB at least 70% of the time.A. Bandwidth EfficiencyWe want to determine how many users that can be supported within a given frequency spectrum. The number of base stations each operator has in a given area will influence how many users that can be supported. If we define M as the average number of users per base station our result will not be influenced by the number of basestations an operator has. The number of users thatcan be supported is proportional to the number of base stations in the area. The modulation scheme, datarate,error control coding etc. will also influence the number of users that can be supported in a specific spectrum. We define B 0 as the bandwidth that an (unspread) carrier will occupy. By dividing the total bandwidth (B) with the bandwidth of one carrier (B 0) we obtain a measure of how many carrier bandwidths the system occupies. Then our measure becomes easy to use for different carrier bandwidths. The bandwidth efficiency can then be defined as:)/(0B B M =η(1)We thus get a number of how many users that on average can be supported per carrier bandwidth and per basestation.MATHEMATICAL ANALYSISIn this section we study the performance of two DS-CDMA systems that coexist in the same spectrum. First we outline the general expression for the performance of these systems. However this is difficult to analyse. Thus we study the special case where the pathloss only depends on the distance from a base station and the user.We also simplify by studying the case with a large bandwidth and many users.Consider a system with unconstrained SIR balancing power control. For the signal to interference in the downlink we get the expression:åå≠=+=K j k M l ijijklkijjij ij kGP NG P 11ηΓ(2)Where Γij is the SIR in the downlink for user i in cell j,P ij is the power transmitted by basestation to user i in cell j, G ijk is the pathloss between user i in cell j and basestation k, N is the processing gain of the system, K is the total number of base stations in the system, M k is the number of users in cell k and ηij is the thermal noise for user i in cell j.Analysing this is difficult since P ij , G ijk and M k are random variables. However if the number of users is large we can simplify by using averages instead since M k →E[M k ] for large M k . If the number of users is large there will be the same number of users M=M k in each cell. The pathloss G can be simplified to only include distance dependence. We introduce r ijk – the distance from user i in cell j to basestation k, α is the propagation loss parameter.α=ijkijk r 1G (3)We introduce P k to be the average power transmitted from basestation k to a user in that cell. Finally ΓT is the target SIR for the power control algorithm. After some reorganisation we get:÷÷øöççèæη+Γ=å≠ααij K j k ijk k ijjT ij r P N M r P (4)In a sir balancing power control scheme the SIR should be constant for all users. Thus we can find out the power that is necessary to transmit for one base station in order obtain a given SIR at a specific user at a specific location. Given that the interference power from the other base stations is constant.It should be noted that if the user is very close to another base station the power necessary to obtain a specific SIR will tend to infinity. The reason is that r ijk →0 close to an interfering basestation. We want to find the average power necessary to support one user, so we average over the whole cell area. In order to limit the average power we exclude a circular area around each interfering base station. It should be noted that excluding a circular area does not result in the lowest average power. The radius of the exclusion circle is set so that the exclusion circles cover 5% of the total cell area. The figure below outlinesthe area (A) that we serve.Figure 2 – The area (A) that is supported by the omnidirectional basestation in the middle. The cell is coexisting with another cellular system using the samefrequency spectrum.It is now possible to find the average power P k that we assumed previously. By averaging over the area A we can determine the average transmission power in the cell we are studying.òòå÷÷øöççèæη+Γ=≠ααA ij K j k ijkkijjT k dxdy r P N M r P (5)However since all cells have the same number of users the average interference power is equal to the average transmitted power is equal in all cells (P k =P). From this we obtain:òòåòò≠αααΓ−ηΓ=AKj k ijk ijj T Aij ijj T dxdyr 1r A 1N M 1dxdy r A 1PM (6)Since the power must be positive we can obtain an upperbound on M/N. Namely:òòå≠ααΓ<A Kj k ijkijj T dxdy r 1r A 11N M (7)The area we excluded corresponds to the users that cannot be supported. We note that by disallowing more users we can obtain higher spectrum efficiency. We also note that for the case of 5% lost users we obtain very low spectrum efficiency.NUMERICAL RESULTSA. DS-CDMAIn our first experiment we investigate the effects of processing gain on the coexistence properties. The figure shows the results. It should be noted that for systems that utilise the spectrum sharing the bandwidth efficiency of the shared system is only 30% of the bandwidth efficiency that can be obtained if the spectrum is given exclusively to one operator.figure shows the bandwidth efficiency for different processing gains. The cell layout is superimposedhexagons and outage probability is 5%.Due to statistical variations the curves are a little bit shaky. More points are simulated around the equiload line which makes the curves. Note that the more bandwidth that is available the lower the bandwidth efficiency becomes. Finally it should be noted that it ispossible to continue the curves by mirroring in the equiload line.B. Location InfluenceWe expect future infrastructures to a large extent be deployed by the end user. We model the location of these base stations as randomly located base stations. When performing numerical experiments we get the results infigure 4.various base station location strategies and 5% outage.Processing gain is 100.We note that the random location of base stations results in lower bandwidth efficiency when only one operator has load. But when both operators has a traffic load the losses are not as severe as for the superimposed hexagons case. This may be explained by the fact that the near far effect is not as pronounced in the random case.C. Frequency HoppingThe figure shows the bandwidth efficiency for different number of available channels. The cell layout is superimposed hexagons, outage probability 5%Here we study what happens if frequency hopping is used as a multiple access method in a shared system.Here we note that the total capacity in the system does not vary depending on the load distribution between the different operators.CONCLUSIONSDS-CDMA not suitable for future infrastructures from a coexistence perspectiveWe can see that the coexistence properties of DS-CDMA systems does discourage use in future communication systems where the radio spectrum is to be shared by many operators. We can see that we loose more than half of the available capacity in a network if we share the spectrum between two operators compared to splitting the spectrum, that means that the cost of building an infrastructure more than doubles for a given capacity. Clearly this is an undesirable property. We note that the losses are mainly due to the near-far effect. There may be ways to improve the performance. Remedies may be to allow handover between operators or by colocating the basestations of both operators.Increased bandwidth in the DS-CDMA case gives worse coexistence propertiesFrom figure 3 we see that by increasing the processing gain in a CDMA system the coexistence properties of a system becomes worse. When the processing gain is high each cell contains many users. That means that each of the base stations will transmit a fairly high power especially to support the users at the cell border. But in the superimposed hexagon placement scheme the base station for one operator is located on the border of the cell of another operator. If the base station transmits a high power that will effectively block out all the users of the other operator that are close to the base station of the first operator. Thus the capacity of the other operator is lowered.Frequency hopping promises good coexistence propertiesWe see that the total capacity of two systems is approximately constant when using frequency hopping. This makes it better suited for coexisting systems. However we can note that the capacity of operator 1 drops when operator 2 increases his traffic. We also note that even though it is not done in this paper it is important to compare the absolute bandwidth efficiency when deciding on which access scheme to use. Orthogonal channels preferableThe near-far problem has a large contribution to the losses when sharing the spectrum. By selecting an access scheme that is not influenced by the near far effect as much we may be able to improve the coexistence properties. Thus orthogonal access methods seems to be preferable.Superimposed hexagons worst caseFrom figure 4 we can see that placement of the base stations influence the coexistence properties for the system. When we use the superimposed hexagons structure we see that the loss due to spectrum sharing is more pronounced compared to the colocated scheme. The loss for colocated base stations is due to the lack of synchronisation between the base stations. Thus interference is created within the cell. The loss in the superimposed hexagons case is due to near far effects. Finally we see that even though the random placement scheme has lower performance than the other schemes for each of the operators the coexistence loss is less.ACKNOWLEDGEMENTSThe author would like to thank Prof. Jens Zander and Dr. Seong-Lyun Kim for reading the manuscript and providing invaluable comments. This paper has been written in the frame of the 4GW project within the PCC strategic research program.REFERENCES[1]M. Flament et al. “An approach to 4th generationwireless infrastructures – Scenarios and key research issues” IEEE 49th Vehicular Technology Conference July 1999 p. 1742-1746[2]J. M. Peha “Spectrum Management PolicyOptions” IEEE Communication Surveys Q4-1998 [3]H. Salgaldo-Galcia, M. Sirbu, J.M. Peha “ANarrowband approach to Efficient PCS Spectrum sharing Through Decentralised DCA Access Policies” IEEE Personal Communications Feb 1997 p 24-34[4]S. Grandhi, J. Zander, R. Yates “Constrained powercontrol” IEEE Wireless Personal Communication vol 1, no 4 1995 p.257-70[5]G. P. Pollini "The Asynchronous Access Etiquettefor the 1910-1920 and 2390-2400 MHz spectrum"IEEE Wireless Communications and Networking conference 1999 p. 584-8。
