A Wireless and Context-Aware ECG MonitorAn iMote2 Based Portable system

神经网络算法与无线传感器网络的关联研究无线传感器网络（Wireless Sensor Networks, WSN）是一种通过大量的分布在空间中的传感器节点收集、处理和传输数据的网络系统。

神经网络算法（Neural Network Algorithm）是一种模仿人类神经系统工作方式的计算模型，能够通过学习和训练来识别和预测模式。

这篇文章将探讨神经网络算法与无线传感器网络之间的关联研究。

首先，我们将介绍无线传感器网络的基本原理和神经网络算法的基本概念，然后讨论两者的结合应用以及研究中存在的挑战和解决方法。

无线传感器网络的关键组成部分是传感器节点，它们能够感知和采集周围环境的物理量。

传感器节点通常包含有限的计算和存储能力，因此需要一种高效的算法来处理数据。

神经网络算法是一种非常有效的数据处理方法，它能够学习和预测模式、优化决策和适应环境变化。

神经网络算法在无线传感器网络中的应用可以包括以下几个方面。

首先，神经网络算法可以用于传感器节点的负载均衡，通过数据预测和分析来选择节点上的任务分配，以实现资源的有效利用。

这可以减少能耗和延迟，并提高网络的性能。

其次，神经网络算法可以用于无线传感器网络中的数据压缩和聚合。

传感器节点通常会产生大量的数据，这些数据需要通过有限的网络带宽传输到中心节点进行处理和存储。

利用神经网络算法可以对数据进行压缩和聚合，减少数据的传输量，提高网络的效率。

此外，神经网络算法还可以用于无线传感器网络中的能量管理和优化。

由于传感器节点通常是由有限电池供电，能量管理是一个重要的问题。

神经网络算法可以通过学习和预测能量消耗模式，为节点提供能量管理策略，延长网络的寿命。

然而，在将神经网络算法与无线传感器网络结合应用时，也存在一些挑战和问题需要解决。

首先，传感器节点的计算和存储能力有限，因此需要设计轻量级的神经网络模型，以适应节点的硬件限制。

其次，传感器网络中的数据通常具有时空相关性，需要考虑这种相关性对神经网络算法的影响。

上海交通大学附属中学2022-2023学年度第二学期高二英语摸底考试试卷(满分150分，120分钟完成。

答案请写在答题纸上。

)命题：张宁审核：程姑第I卷II. Grammar and Vocabulary (20'+20‘)Section ADirections: Beneath each of the following sentences there are four choices marked A,B, C and D. Choose the one answer that best completes the sentence.21.These teenage girls prefer to take pictures________ stands a famous cubism painting in a gallery.A. whereB. whatC. whenD. as22.When guided to reflect on their good fortune, people tend to be more thankful for and appreciative of ________ they have and ________ they are on their path right now, thus more willing to contribute to the common good.A. which, whenB. what, whereC. all, whichD. all, that23.-The wounded soldier ________ have been sent to hospital immediately.-So he ________ , but all efforts made no difference.A. should, wasB. must, didC. ought to, hadD. can, has24.With robots coming to the rescue and appearing on the farm scene, farming has been more efficient with regard to the time ________takes to inspect crops and dig up weed.A. whatB. itC. oneD. which25.We need________ to have a good command of English as a medical student needs ________a doctor.A. as long and tough a training, to becomeB. as long and tough a training, becomingC. as a long and tough training, to becomeD. as a long and tough training, becoming26.The success of Full River Red (Man jiang hong), a 2023 historical suspense comedy film directed by Zhang Yimou, is such________ even some western celebrities have started to read Chinese history.A. asB. likeC. thatD. making27.According to economics, money flows to ________ it is that controls the scarce thing, say, the cutting-edge knowledge.A. whomB. whomeverC. whoD. whoever28.It is natural that the prominent actress ________ charged with tax evasion.A. wereB. would have beenC. may have beenD. should have been29.Premier Li Keqiang is going to take questions from both Chinese and foreign correspondents at the annual press conference_________ in March.A. to holdB. to take placeC. occurredD. held30.Given the serious damage and substantial losses caused by the recent 7.8 magnitude earthquakewhich struck southern Turkey, just 50 miles from the Syrian border, more financial support from international society _________.A. remaining to be raisedB. remains to be raisedC. remaining to raiseD. remains to raise31.The firm has been taking measures to cut costs to keep its _________up, including purchasing cheaper raw materials and reducing its workforce.A. expenditureB. profitsC. salariesD. rank32.The idle afternoon we are going through at home really deserves a fix of coffee or tea to _________our tired minds.A. repairB. refreshC. recoverD. rescue33.General Motors(GM) plans to _________ its two plants to electric vehicle production by 2035 and another plant in Coahuila will make the new model of Chevrolet Blazer from 2024.A. converseB. convertC. conserveD. preserve34.Since the second wave of COVID-19 pandemic in China, investors from home and abroad have lowered expectations of these tech companies, making it harder to lift their _________.A. marketsB. pricesC. brandsD. shares35.A record 3.3 million Americans applied for unemployment _________in the third week of March 2020, according to the US Labor Department, as restaurants, hotels, barber shops, gyms and more shut down in a nationwide effort to slow the spread of the deadly coronavirus.A. claimsB. benefitsC. interestsD. objectives36.On hearing the heart-breaking news, she couldn't _________herself and broke out crying.A. regainB. reserveC. composeD. comprise37.ALK or the gene for anaplastic lymphoma kinase is a stretch of DNA whose mutant (突变的)form has been associated with human cancers, but, its normal function which has something to do with thinness in humans had not been _________before the research.A. foundedB. establishedC. maintainedD. received38.When the candidate presented the results of his experiment on the brain of mice to the pharmaceutical company, they laughed and paid no _________to the discovery which later turned out to be a brilliant idea for a new product.A. investigationB. regardC. noticeD. inspection39.In the 4-day Shanghai Disneyland Tour, you will spend a full day venturing in dream-like Disney castle, gardens, _________ film scenes, enjoying fabulous kid joy with famous Disney characters and various family entertainment activities and amusing shows.A. fancyB. fantasyC. fascinationD. fashion40.The policy _________ "renationalisation”, and throws the country's financial markets back to the past, complains the economist shepherding privatization for the former prime minister.A. accumulatesB. amounts toC. equals toD. recovers Section B:Directions: Complete the following passages by using the words in the box. Each word can only be used once. Note that there is one word more than you need.(A)A. selectedB. distinctiveC. signatureD. odds AB. domestication AC. decidedAD. individuals BC. tamest BD. conflicted CD. mixed ABC. developIf you see a house cat, the_____41_____are high that it will have white paws, a look that many owners affectionately call“socks." But socks are rarely seen in wildcats, the elusive and undomesticated cousin of the house cat, so why do so many pet cats sport furry white feet?As it turns out, this story started about 10,000 years ago, when humans and cats _____42 _____ life was better together.This_____43 _____eventually led to uber-prevalent socks on cats, as well as other well-known coat patterns, said Leslie Lyons, professor emerita and head of the Feline Genetics Laboratory at the University of Missouri College of V eterinary Medicine.“As humans became farmers and started staying in one place, they had grain stores and waste piles” that attracted rodents, Lyons said. It was a mutually beneficial arrangement: the humans had fewer rodents to deal with and the cats got an easy meal.The wild, undomesticated ancestor species of house cats, Felis silvestris, lives in Africa and Eurasia. These felines are tasty snacks as kittens and stealthy predators as adults, so _____44 _____ born with a coat that offers camouflage (保护色)have tended to survive and reproduce.But not every F. silvestiis is born with a coat that blends into its habitat."Genetic mutations are occurring all the time.” Lyons said.There isn't much evidence to indicate why early cat people chose the individuals they did, but Lyons said the range of coats seen on modern domestic cats shows that our agrarian ancestors favored cats with markings that would have _____45 _____with their camouflage.In its native mixed forest or scrub desert environment, a cat with stark white paws would have stood out to predators and prey.When humans started taking an interest in cats, these white paws would have stood out to them, too. “There were probably people saying,‘I particularly like that kitten because it has white feet . Let's make sure it survives, Lyons said.Humans probably also_____46 _____cats who were calm and comfortable around humans, Lyons said. Behavioral traits seem unrelated to coat color, but for reasons that scientists don't fully understand, white spots tend to appear when the _____47 _____individuals are selected and bred.These_____48_____fur colors and markings emerge while a cat embryo is developing. The cells that give cat fur its color first appear as neural crest cells, which are located along what will become the back, Lyons said.Then, those cells slowly migrate down and around the body. If those waves of cells move farenough to meet each other on the cat's front side, the embryo will be born a solid-colored kitten, such as an all-black or all-orange cat. Felines _____49 _____white feet, faces, chests and bellies when these cells don't quite make it all the way.So, the next time you see a kitty wearing white socks, you'll know that this _____50 _____ feature is a result of genetic mutations, domestication and developmental biology. Although if you try telling the cat that, it will probably just look at you quizzically before sauntering away.(B)A. initiallyB. formedC. societiesD. map AB. officiallyAC. constructed AD. potentially BC. investigate BD. perspective. CD. boundaries ABC. considerationConstruction of the world's largest radio astronomy observatory, the Square Kilometre Array, has_____51_____begun in Australia after three decades in development.A huge intergovernmental effort, the SKA has been hailed as one of the biggest scientific projects of this century. It will enable scientists to look back to early in the history of the universe when the first stars and galaxies were _____52_____.It will also be used to _____53 _____dark energy and why the universe is expanding, and to _____54 _____search for extraterrestrial life.The SKA will _____55_____ involve two telescope arrays---one on Wajarri country in remote Western Australia, called SKA-Low, comprising 131,072 tree-like antennas. SKA-Low is so named for its sensitivity to low-frequency radio signals. It will be eight times as sensitive than existing comparable telescopes and will _____56 _____the sky 135 times faster.A second array of 197 traditional dishes, SKA-Mid, will be built in South Africa's Karoo region.Dr Sarah Pearce, SKA-Low's director, said the observatory would "define the next fifty years for radio astronomy, charting the birth and death of galaxies, searching for new types of gravitational waves and expanding the_____ 57 _____of what we know about the universe'1.She added: "The SKA telescopes will be sensitive enough to detect an airport radar on a planet circling a star tens of light years away, so may even answer the biggest question of all: are we alone in the universe?"The SKA has been described by scientists as a gamechanger and a major milestone in astronomy research."To put the sensitivity of the SKA into _____58 _____, it could detect a mobile phone in the pocket of an astronaut on Mars, 225m kilometres away,” said Dr Danny Price, a senior postdoctoral fellow at the Curtin Institute of Radio Astronomy." More excitingly, if there are intelligent _____59 _____ on nearby stars with technology similar to ours, the SKA could detect the aggregate 'leakage' radiation from their radio and telecommunication networks~the first telescope sensitive enough to achieve this feat."Prof Alan Duffy, director of the space technology and industry institute at the Swinburne University of Technology, said the SKA would probably be the largest telescope _____60 , _____,"connecting across continents to create a world-spanning facility allowing us to see essentially across the entire observable universe".III. Reading Comprehension (15'+22'+8‘)Section ADirections: For each blank in the following passage there are four words or phrases marked A, B, C and D. Fill in each blank with the word or phrase that best fits the context.The economic case for regiftingDespite its pleasures, gift giving can be problematic.A recipient wants items A andB (say, a hat and gloves) yet receives itemsC andD (say, a scarf and mittens). Another recipient wants C and D, yet receives A and B. The_____ 61 _____ seems simple: The two recipients can simply pass along the gifts they received to each other.The _____62_____ however, is more complex. People in a study published in the Journal of Consumer Behaviour, for instance, used such words as guilty, lazy, thoughtless and disrespectful in describing their_____63 _____ about regifting. Popular culture casts it as taboo, as well.Getting stuck with gifts we do not want is no small problem. Consider that the National Retail Federation calculated that the average holiday-season______64 _____in the U.S. last year spent more than $1,000 on gifts. In a survey across 14 countries in Europe, meanwhile, 1 in 7 said they were unhappy with what they received for Christmas, yet more than half simply kept the gifts.Why can't more gifts be passed along to people who _____65 _____them?Our research with Francis J. Flynn, a professor of organizational behavior at Stanford University's Graduate School of Business, suggests the shame associated with regifting is largely _____66 _____. Indeed, our research consistently tells us that people overestimate the negative consequences.We conducted a study in which we asked people to imagine themselves either as a "giver,” who gives someone a gift card and later _____67_____it has been regifted; or as a "regifter," one who receives the gift and gives it to someone else. The latter group saw more offense. Regifters tended to assume the original givers would be _____68_____ when they found out. The general _____69_____ of the original givers, however, was: It's your gift, do what you want with it.”Next, we tried to shed light on just how serious the perceived offense is. We asked two group —again givers and regifters—to______70_____ regifting a hypothetical （假设的）wristwatch with throwing it in the trash. For the original givers, regifting the watch was a much less offensive act than trashing it. The regifters, however, _____71 _____ assumed that the givers would find both equally offensive.Finally, given that the feared offense looks more imagined than real, we turned our attention to how people might be_____72_____ to break this taboo.For this part of our research, we invited to our lab at Stanford people who had recently received presents and divided the people into two groups. When we gave the first group an opportunity to_____73_____that present, 9% did so.When we gave the second group the same opportunity, we added that it was '"National Regifting Day,” a real______74 _____that happens each year on the Thursday before Christmas. It wasn't really National Regifting Day, but the group didn't know that: 30% of them agreed to regift.Everyone has received bad gifts in their lives, and we generally accept that we will receive more in the future. Yet for some reason, we believe that we give only good gifts.Our research offers a simple solution to the problem of _____75 _____ gifts. This holiday season, consider regifting, and encourage people who receive your gifts to do the same if what you give them isn't quite what they hope for.61.A. result B. cycle. C. trick D. solution62.A. cause B. psychology C. science. D. theory63.A. feelings B. ideas C. trick. D. evaluations64. A. citizen B. retailer C. shopper D. foreigner65. A. refuse B. appreciate C. envy D. collect66. A. perceived B. ignored C. unjustified D. immeasurable67. A. learns B. suspects C. complains D. imagines68. A. praised B. hurt C. hateful D. grateful69. A. motto B. code C. principle D. attitude70. A. replace B. connect C. compare D. exchange71. A. desperately B. voluntarily C. responsibly D. wrongly72. A. encouraged B. pushed C. challenged D. forced73.A. hide B. sell C. regift D. decline74. A. ceremony B. celebration C. day D. event75. A. unpopular B. unwanted C. expensive D. meaninglessSection BDirections: Read the following three passages. Each passage is followed by several questions or unfinished statements. For each of them there are four choices marked A, B, C and D. Choose the one that fits best according to the information given in the passage you have just read.(A)Jailbreaking commonly refers to unlocking iOS for iPhones and iPads. Seventeen-year-old George Hotz, or geohot as he liked to be called, was the first person to jailbreak an iPhone. He accomplished his feat in 2007, and many others followed his lead.Jailbreaking an iPhone offers some distinct benefits. With a jailbroken iPhone, you have numerous ways to change any setting to suit your needs. You can also alter the look and feel of the phone so that it matches your personality. Another advantage of jailbreaking for iPhone users is the ability to install apps not offered in Apple's App Store. Cydia, an alternative app store for jailbroken iOS devices, offers a variety of apps, some of which cost more than others.Before jailbreaking your iPhone, you should consider the consequences. Jailbreakingimmediately voids (使无效)your iPhone's warranty, which means that Apple is no longer required to fix your phone if something goes wrong. Jailbreaking also exposes you to the dangers associated with alternative apps. Poor quality apps from alternative app stores may cause your iPhone to crash more often or stop working altogether. After jailbreaking your iPhone, you must also be careful not to allow Apple to install new software on your phone.Apple naturally discourages its customers from jailbreaking their iPhones. According to the company, jailbreaking doesn't just affect the security and stability of an iPhone. It can also shorten the phone's battery life. For many people, this is an important consideration.76. Which aspects of jailbreaking does the article discuss?A. The ways in which jailbreaking can save people timeB. The positives and negatives associated with jailbreakingC. The clients who got into legal trouble for jailbreakingD. The best and worst techniques for jailbreaking phones77.What does the article imply about the first person to jailbreak an iPhone?A. He apologized for his actions.B. He produced hardware designs.C. He gave himself a nickname.D. He was turned down for a job.78.From this article, what can readers learn about the products offered by Cydia?A. Their prices vary somewhat.B. Their inventors are quite young.C. They're still manufactured abroad.D. They take only a few moments to install.79.According to Apple, what might happen after a person jailbreaks his or her iPhone?A. It might need a new camera stand.B. It might become harder to sell.C. It might be easily damaged by water.D. It might use up its battery faster.(B)Vanuatu is an island nation in the South Pacific. It is also one of the smallest countries in the world. But for those interested in adventure and sport, there is a lot to do. Some of the best snorkeling (浮湖) can be found here. Vanuatu's islands also offer visitors two of the most exciting and dangerous activities in the world: volcano surfing and land diving.Volcano SurfingOn Tanna Island, Mount Yasur rises 300 meters (1,000 feet) into the sky. It is known as the Lighthouse of the Pacific because of its regular eruptions for hundreds of years. For centuries, both island locals and visitors have climbed this mountain to visit the top. Some visitors find Yasur terrifying; others cautivating. Photographers are beside themselves at the opportunity to make stunning artwork from such a special point. Recently, people have also started climbing Yasur to surf the volcano.In some ways, volcano surfing, also commonly known as ash boarding, is like surfing in the sea, but in other ways it’s very different. It was invented by an adventurer journalist named Zoltan Istvan, while on a trip to Vanuatu Islands in 2002. V olcano surfing is considered as an extreme sport and there are not many practicing it. A volcano surfer's goal is to escape the erupting volcanowithout getting hit by flying rocks! Riders hike up the volcano and slide down, sitting or standing, on a thin plywood or metal board. It's fast, fun, and dangerous—the perfect extreme sport.Land DivingMost people are familiar with bungee jumping, but did you know bungee jumping started on Pentecost Island in Vanuatu and is almost fifteen centuries old? The original activity, called land diving, is part of a religious ceremony. A man ties tree vines (藤) to his legs. He then jumps headfirst from a high tower. It originated as a rite (仪式) of passage for young men trying to prove their manhood. The idea is to jump from as high as possible, and to land as close to the ground as possible. It is also a harvest ritual. The islanders believe the higher the jumpers dive, the higher the crops will grow. Every spring, island natives (men only) still perform this amazing test of strength.80.Which of the following can be learned from the passage?A. Mount Yasur is a light tower on the Pacific Ocean.B. The history of volcano surfing dates back centuries.C. Bungee jumping grew out of land diving.D. Land diving came to Vanuatu from another country.81.The underlined word captivating is closest in meaning to _______.A. distressingB. charmingC. disappointingD. relieving82.Which of the following could be the best title of this passage?A. Untouched Beauty: V ANUA TUB. V olcano Adventure: V ANUATUC. Extreme Destination: V ANUA TUD. Preserved Culture: V ANUATU(C)The water off the coast of northwest Greenland is a glass-like calm, but the puddles (水坑)on the region's icebergs are a sign that a transformation is underway higher on the ice sheet.Several days of unusually warm weather in northern Greenland have caused rapid melting, made visible by the rivers of meltwater rushing into the ocean. Temperatures have been running around 60 degrees Fahrenheit—10 degrees warmer than normal for this time of year, scientists said.The amount of ice that melted in Greenland between July 15 and 17 this year alone—6 billion tons of water per day~~would be enough to fill 7.2 million Olympic-sized swimming pools, according to data from the US National Snow and Ice Data Center,Each summer, scientists worry that they will see a repeat of the record melting that occurred in 2019, when 532 billion tons of ice flowed out into the sea. An unexpectedly hot spring and a July heat wave that year caused almost the entire ice sheet's surface to melt. Global sea level rose permanently by 1.5 millimeters as a result.Greenland holds enough ice一if it all melted一to lift sea level by 7.5 meters around the world. The latest research points to a more and more threatening situation on the Northern Hemisphere'siciest island.“Unprecedented" rates of melting have been observed at the bottom of the Greenland ice sheet, a study published in February found, caused by huge quantities of meltwater flowing down from the surface. This water is particularly concerning because it can destabilize the sheet above it and could lead to a massive, rapid loss of ice.And in 2020, scientists found that Greenland's ice sheet had melted beyond the point of no return. The rate of melting in recent years exceeds anything Greenland has experienced in the last 12,000 years, another study found—and enough to cause measurable change in the gravitational field over Greenland.At the East Greenland Ice-core Project~ or EastGRIP—research camp in northwest Greenland, the work of scientists to understand the impact of climate change is being affected by climate change itselfAslak Grinsted, a climate scientist at the University of Copenhagen's Niels Bohr Institute, said that they have been trying to get flights into the camp but the warmth is destabilizing the landing site.Before human-caused climate change kicked in, temperatures near 32 degrees Fahrenheit there were unheard of. But since the 1980s, this region has warmed by around 1.5 degrees Fahrenheit per decade—four times faster than the global pace—making it all the more likely that temperatures will cross the melting point.83.The passage is mainly written to _______.A. alert people to the rapid melting of Greenland's ice sheetB. arouse people's awareness of protecting the environment of GreenlandC. inform people of the large amount of ice Greenland holdsD. reveal to people the cause and effect of the rise in sea level84.What does "a transformation” in the first paragraph refer to?A. Climate change.B. A rise in sea level.C. Global warming.D. The melting of ice.85.What can be learned about the ice that melted in 2019?A. It repeated a record melting of the ice sheet several years ago.B. Its amount was the largest ever and lifted sea level permanently.C. It was enough to fill 7.2 million Olympic-sized swimming pools.D. Its melting rate was so rapid as to result in an unexpectedly hot spring.86.It is implied in the passage that _______.A. climate change is a result of human activitiesB. the study of climate change is being made easierC. the melting of Greenland's ice sheet is reversibleD. temperatures increase 1.5°F or so each decade globallySection CDirections: Read the following passage. Fill in each blank with a proper sentence given in the box. Each sentence can be used only once. Note that there are two more sentences than you need.A. They also found cetaceans gained and lost TSGs at a rate 2.4 times higher than in other mammals.B. If the whale gene was injected into the human body, could humans fight cancer?C. Some people deny that cetaceans can increase TSGs faster than other mammals.D. If you have more cells that means that one of those cells has an increased risk of becoming cancerous.AB.In contrast, cetaceans have much lower cancer rates than most other mammals.AC.But we still need to learn more about why and how they did this.Can Whales And Dolphins Fight Cancer?Whales and dolphins have been shown to be better at fighting cancer than we are, and now we may be closer to understanding why cetaceans (鲸目动物)do it. Cetaceans are generally the oldest living mammals, and some cetaceans have reached their 200th birthday. Their size means their bodies contain far more cells than the human body."_______87_______” says Daniela Tejada-Martinez at the Austral University of Chile. “So, if you are big or live longer, you have thousands and millions of cells that could become harmful." _______88_______“There's a joke that whales should be born with cancer and not even able to exist because they're just too big,” says Vincent Lynch at the University at Buffalo, New York, he says there is a super trivial explanation for how whales can exist. "They just evolved better cancer protection mechanisms," he says. ______89 _______Now, Tejada-Martinez and her colleagues have studied the evolution of 1077 tumor suppressor (肿瘤抑制)genes (TSGs). In all, they compared the evolution of the genes in 15 mammalian species, including seven cetacean species, Genes regulating DNA damage, tumor spread and the immune system were positively selected among the cetaceans. _______90 _______“It's not like we're gonna be taking whale genes and putting them into humans and making humans cancer resistant,” says Lynch. "But if you can find the genes that play a role in tumor suppression in other animals, and if you can figure out what they're doing, maybe you can make a drug that can be used to treat people."第II卷IV Grammar (10+10)Directions: After reading the passages below, fill in the blanks to make the passages coherent and grammatically correct For the blanks with a given word, fill in each blank with the proper farm of the given word; far the other blanks, use one word that best fits each blank.(A)When Steve Birkinshaw, the British fell running (越野路跑)champion, planned his record-。

用菲涅尔区模型探究WiFi 感知系统的稳定性牛凯1,2，张扶桑3，吴丹1,2，张大庆1,2+1.北京大学信息科学技术学院高可信软件技术教育部重点实验室，北京1008712.北京大学（天津滨海）新一代信息技术研究院，天津3004503.中国科学院软件研究所计算机科学国家重点实验室，北京100190+通信作者E-mail:*************** 摘要：基于WiFi 的非接触感知系统利用环境中广泛存在的WiFi 信号在自然情况下对用户活动进行感知，具有十分广阔的应用前景。

从细粒度活动到粗粒度活动，现有工作进行了大量的探索，但尚未理解和解决感知系统稳定性不足的问题。

当感知对象、收发设备位置、测试环境等发生变化时，系统性能会受到严重影响。

实际上，人体活动对应的接收信号模式因位置和朝向的变化而带来的不一致性导致了系统不能稳定工作。

为了理解这种现象的本质，利用团队提出的基于无线感知的菲涅尔区衍射和反射模型，精确定量刻画了目标物体相对于收发设备的位置、运动轨迹和无线信号波形模式之间的关系。

通过两个应用实例，即细粒度的手指动作识别和粗粒度的健身活动识别，在模型的指导下，分别解释了系统不能稳定工作的原因，说明了如何得到一致的感知波形，以及如何构造可区分的感知波形，并给出了提升感知系统性能的方法。

关键词：菲涅尔区模型；系统稳定性；WiFi ；无接触感知文献标志码：A中图分类号：TP399Exploring Stability in WiFi Sensing System Based on Fresnel Zone ModelNIU Kai 1,2,ZHANG Fusang 3,WU Dan 1,2,ZHANG Daqing 1,2+1.Key Laboratory of High Confidence Software Technologies,Ministry of Education,School of Electronics Engineering and Computer Science,Peking University,Beijing 100871,China2.Peking University Information Technology Institute (Tianjin Binhai),Tianjin 300450,China3.State Key Laboratory of Computer Sciences,Institute of Software,Chinese Academy of Sciences,Beijing 100190,China Abstract:WiFi based contactless sensing systems use pervasive wireless communication signals in the environment to sense human activities in a natural way,enabling many promising applications.From fine-grained activity sensing to coarse-grained activity recognition,existing work have done a great deal of exploration.However,there is lack of understanding and tackling the serious unstable sensing performance problem.While changing the human target,the position of transceivers,and test environment,the system performance is severely degraded.The reason behind the instability of WiFi-based sensing system is that human activities induce the inconsistent signal patterns inherently at different positions.This paper proposes the Fresnel zone-based diffraction and reflection sensing model,which can计算机科学与探索1673-9418/2021/15(01)-0060-13doi:10.3778/j.issn.1673-9418.1912017基金项目：国家自然科学基金（61572048，61802373）；北大百度基金资助项目（2019BD005）；中国科学院青年创新促进会项目（2020109）。

W-TRACKER ®Wireless Head TrackerInstruction ManualOVE R V IEWW-Tracker R is a state of the art wireless inertial head tracking system intended for FPV flightand based on inertial sensors to determine the FPV pilot head relative position to the ground.The system consist in a set of 2 units, a RF transmitter (TX) module that includes the inertial sensors and a RF receiver (RX) Buddy Box module that includes the PPM interface with the RC model controllers.The TX sensor module is RF (FM) linked to the R-Tack R RX interface module using the 433MHz ISM Band. 10 different RF Channels are available to allow the use of up to 10 R-Track R units simultaneously.Transmitter Head Tracker Buddy Box ReceiverR-Tack R includes 3 cables:1.- Head Tracker supply cable.2.- Futaba connector for stand – alone use3.- Futaba connector for master – slave use.W-Tracker R is designed to be used with a single transmitter, or between a trainer transmitter,and a student transmitter. When used in Master - Slave mode, The student Tx is supplied through the W-Tracker R .The connectors on the W-Tracker Rmodules are standard 3.5mm 4pin jack receptacles in order to make the system compatible with several radio models. See annex for pin-out reference.W-Tracker R is shipped with a power supply cable compatible with the Fatshark RCV922 headset battery connector. For other FPV headsets, please check annex to adapt or build thepower supply cable. Same happens with the transmitter connectors, R-Tack Ris shipped with Futaba connectors, but connectors as WFLY and others can be used, please check annex to adapt or build the transmitter cables.H E A D T R A C K E R M O D U L EThe Head tracker module includes the inertial sensors, and a 433MHz micro FM transmitter.In the top of the HT there is a bicolour movement indicator light and a pushbutton for configuration purposes.In the Bottom Side there is a rotary switch to select the radio channel to be used. It is possible to use up to 10 W-Tracker R simultaneously. You should select the same channel in the Head Tracker module and in the buddy box module.There is a 4 pin 3.5mm jack receptacle in the right side of the HT that supplies the HT unit with the same 2S Li-Po battery that supplies the FPV headset.Battery Output Activity LEDConfigurationPush-ButtonIt is recommended to use a velcro-type adhesive tape to mount the Head Tracker on the FPV headset.The battery power connectors are connected in parallel, so once connected to the battery they are supplying power to the Head Tracker. This is important because if you are not using the Head Tracker it is recommended to disconnect the battery from the power supply connector to avoid a complete discharge of the headset battery.Before fixing the Head Tracker on the headset, you should set the HT channel frequency. Use the same plastic screwdriver used for the channel frequency selection in the RC transmitter.Once selected the channel you can mount the Head Tracker on the FPV headset.Battery Input Channel Select Rotary Switch512 34 6 9 8 7Adjusting SensitivityThe horizontal movement sensitivity can be set with the Push Button. The W-Tracker R allows 3 sensitivity modes: High, Medium and Low. Sensitivity affects to the motion threshold detection.W-Tracker R determines horizontal position only when you move your head, so if you are moving continuously the HT, there will be a cumulative error position. In the highest sensitivity mode, even a very slow movement will be detected by the HT, so the probability to experiment error position will be higher, in the other side, the movement is detected instantaneously. By lowering the sensitivity you will have less error position.By pushing continuously the push button, the HT will show you first a red light (High Sensitivity), after a green light (Medium Sensitivity) and finally an orange light (Low Sensitivity). By releasing the push button when the light is in the desired colour, you will set the sensitivity.Cold StartWhen HT starts it determines the “zero position” and during this process it is mandatory to keep still the HT. Once determined the “zero position”, the green light will blink during 2 minutes (approx) what means the HT is performing temperature compensation.If during starting process the Red Led is continuously blinking, it means that it cannot determine the zero position, so you should disconnect the unit from the battery and reconnect after 3 seconds again.OffsetSystem is designed to cancel the horizontal drift, but in exceptional cases, if you observe any drift, just stop completely your head and wait until the servo motion stops, after that any drift will disappear.If during the use of the HT you experiment any offset position (due to the cumulative errors), you can compensate it by moving your head to the operation limit side of the deviation; by exceeding the HT detection limit you will set a new offset (opposite to the original) to the movement that will cancel the original offset.zero Right Limit Left Limit Working normally (without offset)In both cases, the HT takes the last position (beyond the limit) as the new limit, and allows the user the offset correction.B U D D Y B O X M O D U L EThe Buddy Box module has 2 x 3.5mm 4 PIN jack receptacles ‘A’ and ‘B’ as follows:There are also 2 connectors for the RC transmitters:Left offset correction by moving your head beyond the Left limit Right Limit Right offset correction by moving your head beyond the Right limitoffsetA BCable for Master RC Transmitter(teacher)Cable for Slave RC Transmitter(student)SHORT CABLE LONG CABLEThe Buddy Box works generating or reading PPM streams from the RC transmitters. It reads PPM signals from receptacle B and transmits PPM signals trough receptacles A and B.Buddy Box working modes are:• “PPM GEN” Stand Alone ModeIn this mode the Buddy Box generates a PPM data stream like a student RC transmitter; when the trainer function is activated on the RC transmitter, the channels associated to the Pan & Tilt motion will be activated.This mode can only be used if your TX has the option to disable the trainer channels not used for the Pan & Tilt Function.This mode is typically used when the RC system is working in PCM Mode and the student RC transmitter is not connected, although it can be also used in PPM mode.You should use the short cable to connect the RC transmitter to the Buddy Box receptacle A or B (it doesn’t matter).• “PPM FeedBack” Stand Alone ModeIn this mode the Buddy Box reads the PPM data stream from your RC transmitter and inserts the Pan & Tilt information on the PPM stream. Once done that, it feeds back the PPM stream to your RC transmitter again. When the trainer function is activated on the RC transmitter, the channels associated to the Pan & Tilt motion will be activated.If your TX has not the option to disable any trainer channel, you should use this operation mode, remember to set your RC transmitter in PPM to work in this mode.This mode is typically used with RC transmitters that cannot disable the not-used trainer channels and the student RC transmitter is not connected.You should use the short cable to connect the RC transmitter to the Buddy Box receptacle B.A B B• Teacher - Student ModeIn this mode the Buddy Box reads the PPM data stream from the Student RC transmitter and inserts the Pan & Tilt information on the PPM stream to the Teacher RC transmitter. When the trainer function is activated on the Teacher RC transmitter, the channels associated to the Pan & Tilt motion plus the student channels will be activated.This mode is typically used in Teacher – Student Mode. Remember to set the Student RC transmitter in PPM mode. Teacher RC Transmitter may be in PPM or PCM.You should use the short cable to connect the Teacher RC transmitter to the Buddy Box receptacle A, and use the long cable to connect the student RC transmitter to the Buddy Box receptacle B.Student TeacherTeacherPPM or PCMStudentPPMB U D D Y B O XC O N F I G U R A T I O NTo enter in configuration mode, push the config. button during 0.5s and release it; after that a green LED will blink showing the different configuration options:Option 1Option 2Option 3 Sub option 1Sub option 2Sub option 3. . .Option “n”If you want to enter into the Option Menu, just push the config button again and you will enter into the sub-menu; then a red LED will blink showing you the submenu options. To change the configuration option, push again the config button. The buddy boxwill acknowledge your choice by flashing red and green leds. After that it will continue with the next option menu.R-Tack Rconfigurable options are the following:PPM Mode: GEN / PPM Feed Back PPM Modulation: PPM+ / PPM- Number of Channels:6 to 8....... (4 times) Extended mode: Normal / Extended ....... (5 times) Pan motion invert: Normal / Inverted ....... (6 times) Tilt motion invert: Normal/ Inverted ....... (7 times) Disable motion: No Disable / Disable Pan / Disable TiltMinimum number of channels is 6. Default options are shown in red.Futaba Transmitters use PPM- Modulation.Once defined the number of channels, the buddy box will put the Pan & Tilt information into the last 2 Channels, for example, if you programmed “Number of Channels” = 6, Pan & Tilt are in channels 7 and 8.Push config. button during 0.5s and release it to enter in the configuration mode Push config. button during 0.5s and release it to modify option 3Push config. button during 0.5s and release it to select suboption 3Number of Channles = 8 Buddy BoxAcknowledgement“Extended mode” is intended to fix the Pan & Tilt information on channels 7 and 8; for example, if you programmed “Number of Channels” = 6, Pan & Tilt information will be set in channels 7 and 8, extending the number of channels of your RC transmitter from 6 to 8. Another example, if you programmed “Number of Channels” = 6, Pan & Tilt information will be set in channels 7 and 8, extending the number of channels of your RC transmitter from 7 to 8.This function could not work in all RC controllers.To restore default options, push configuration button and keep it pushed during 3 seconds, after that, release it and it will reload the default options shown previously.A N N E XBuddy Box Connectors Pin-Out:Head Tracker Pin-Out:。

多模态行为与情感智能感知关键技术及应用Multi-modal behavior and the key techniques andapplications of emotion-aware intelligence perception.Emotion plays a crucial role in human communication and decision-making. It is not solely conveyed through verbal expressions, but also through various nonverbal signalslike facial expressions, body language, tone of voice, and even physiological responses. In recent years, there has been increasing interest among researchers in developing technologies that can detect and comprehend emotions from multi-modal behaviors. This field is known as emotion-aware intelligence perception.情感在人类的交流和决策中起着关键的作用。

不仅通过口头表达方式传递，还通过各种非语言信号传递，如面部表情、肢体语言、语调甚至生理反应。

近年来，研究者们对于开发能够从多模态行为中检测和理解情感的技术越发感兴趣。

这个领域被称为情感智能感知。

In order to achieve emotion-aware intelligence perception,researchers have utilized various sensing modalities such as computer vision, audio analysis, physiological sensors, and natural language processing. By combining information from multiple modalities, machines can better understand and capture subtle emotional cues that are often missed by analyzing a single modality alone.为了实现情感智能感知，研究者们已经利用了各种传感模式，如计算机视觉、音频分析、生理传感器和自然语言处理。

||Volume||2 ||Issue|| 7 ||Pages|| 30-34||2013||ISSN(e): 2319 – 1813ISSN(p):2319 – 1805Design and Simulation of Range Estimation In ResidentialBuilding Using IEEE 802.11b WLAN Networks.Vijay Rayar1,2,Department of Electronics and Communication Engineering, KLE Dr. M. S. Sheshgiri College OfEngineering & technology, Belgaum--------------------------------------------------------ABSTRACT------------------------------------------------------------Location estimation is a critical step for many location aware applications. In this paper we present cost effective and simplified location estimation in residential building. The technique is based only on Received Signal Strength Index (RSSI) measurements taken at receiver nodes using WLAN cards. The localization performance is computed in terms of Cramer-Rao Lower Bound (CRLB) of range estimate under residential environments which is relatively less complex computation technique. This system is designed and tested in MATLAB tool. Simulation results reveal that the CRLB range estimation has better performance than the multilateration with linearization for access point localization algorithm and Eglis propagation model. KEYWORDS : CRLB, Indoor localization, WLAN, MATLAB, RSSI.Date of Submission: 8 July 2013, Date of Publication:25 july,2013I.INTRODUCTIONThe need for localization of wireless nodes in a wireless network is of great importance. The location information is necessary in positioning, tracking, context aware applications. The most commonly used localization technique is the global positioning system (GPS). The indoor localization system has passed through a lot of improvements over the years. From the global positioning system (GPS) and the time of arrival (TOA), to the time difference of arrival (TDOA) and the received signal strength (RSS), researches have been on in areas of analysis and improvements. Among the techniques listed above, only the RSS technique is used mainly for indoor environment. A lot of researches are being under taken in the indoor localization system because of its interesting applications and the numerous factors that affect the propagation of radio frequency (RF) signals in an indoor environment. The indoor radio propagation channel is characterized as site-specific, severe multipath fading and low probability of line-of-sight (LOS) signal propagation path between the transmitter and the receiver [1]. The main contribution of this work is to present improved localization estimation technique. The method proposed exhibits higher localization accuracy, is calibration free and simple. The CRLB‘s presented in this paper quantify the localization performance. The proposed method demonstrates better performance as compared to the multilateration for AP localization and Eglis propagation model.II.CRAMER – RAO LOWER BOUNDParameter estimation in many signal processing systems is designed for applications in:∙Instrumentation —estimate the sinusoidal signal amplitude for DSP based instrumentation [2].∙Power systems —estimate the time varying frequency for single phase electric systems.∙Speech Processing —estimate the spectral envelope and fundamental frequency component.∙Radar systems- estimate target velocity for multi input-multi output radar.In estimation technique the estimator takes the measured data as an input and produces estimate of the parameters. Cramer-Rao lower bound (CRLB) is the widely used estimator and also the estimation method in evaluating performance of wireless localization [2]. The RSSI model and associated CRLB are assessed in this section. The real time RSSI value obtained by the mobile node is taken as Gaussian random variable. Using the log normal shadowing signal propagation model RSSI values are given by:(1) where α is the power measured at a reference distance do assumed to be of 1 m, d is the distance betweenmobile node and the access point (transmitter), n is the path loss exponent, X denotes a Gaussian randomvariable with zero mean caused by shadowing. The power measured at a reference distance, α depends onseveral factors: fast and slow fading, antenna gain, and transmitted power.In general, CRLB is defined as the theoretical lower bound for any unbiased estimator of an unknownparameter . CRLB is obtained for the range dependent model described in Eq. (1) as [2] [5],(2)where is the maximum likelihood estimator (MLE) of distance between the access point and the i th positionσi is the standard deviation of P Ri measurements at the i th location. Given the measurements P Ri at the i thlocation, the maximum likelihood distance from access point is given by,(3)The MLE offers a straightforward solution to convert RSSI values into range estimates. Error can beformulated as,Error = Actual distance – Estimated distance= d i–III.EXPERIMENTAL SETUPThe Performance of wireless node localization is carried out in residential building i.e., PrashanthNilay resides in Belgaum, where AP is located at fixed height and the mobile node can be placed anywhere inthe propagation environment or line of sight scenario (LOS). The realistic RSSI measurements are collected inLOS scenario as shown in fig. 1 below.Figure 1: Floor layout for localization performance evaluationFigure 2: Snapshot of Net StumblerThe figure 1 and 2 shows the floor plan of residential building which has area of 69.16m2 and RSSI measurements are collected using net stumbler [3] software. The Wireless router (NetGear) with a uniquemedium control address is used as an access point. The snap shot of the measurement of RSSI in residentialbuilding is as shown in fig. 3.The Standard Deviation of measured RSSI is 7.1899 dB.Figure 3: Prshanth Nilay Belgaum.IV.SIMULATION RESULTS4.1 Relation between RSSI and DistanceReceived signal strength (RSS) values were measured within 10 meters of the access point (AP) with a step size of 0.5 meter. These measurements were repeatedly taken at different times in the same scenario. A possible method of predicting the RSS within the test bed environment is by using of a mathematical model given as [4],P r= -10n log10d+ α (5) Where in above eqn (5),P r is RSS, n is the path loss exponent, d is the distance between access point and mobile node and α is the power level measured at 1 meter distance form access point. This relationship is obtained using curve fitting tool from collected RSSI in residential building and shown in fig. 4.and they are linearly related.Figure 4: Relation Between RSSI and DistanceThe Signal Propagation Model is given by,P r = -40 – 29 log10(d) (6)Comparing eqn (6) with eqn (5) the value of ‗n‘ and ‗α‘ can be estimated which can be used in CRLB computation. According to this,α =-40 dBmn = 2.94.2 Comparison Proposed method With Multilateration with RSS linearizationIn this section we make a comparison between the proposed model in both residential building with the other existing localization algorithms. Fig. 5 shows the comparison of range estimation in residential building respectively. It shows that CRLB range estimating technique is better than other two techniques, Multilateration with RSS Linearization and Eglis propagation model [6], which is having less error comparing to others.Table 1: Comparison of Mean Error in meters Of Three TechniquesTable 1 gives the comparison of mean distance error by using three different techniques in meter they are the proposed model with path loss exponent 2.9 from signal propagation model obtained by measured RSS, multilateration with RSS Linearization for AP localization and Eglis Propagation model.V.CONCLUSIONOur work focuses on localization performance improvement in LOS scenario by placing the access point at fixed height. The CRLB computations based on real time RSSI values are used to evaluate the localization performance. The presented approach is calibration free and less complex. The proposed method gives better localization accuracy as compared to multilateration with linearization algorithm for AP localization and Eglis propagation model..REFERENCES[1]J.Agajo, O. joseph, E.Ezewele and A. Theophilus, Spatial Analysis of Signal Strength in a Wireless Communication Medium for IndoorGeolocation System International Journal of Computer Theory and Engineering, vol 3, No 4, August 2011.[2]Udaykumar Naik, Vishram N. Bapat, Access Point Height Based Location Accuracy Characterization in LOS and OLOS Scenarios.Wireless Personal Communication Springer Science+ Business media New York 2012.[3]NetStumbler [4]Oguejiofor O.S, Okorogu V.N, Nwalozie G.C, Adewale Abe ―Indoor PropagationPrediction in Wireless local Area Network‖. IJEIT Volume 2, Issue 4, October 2012.[5]Santiago Mazuelas, Alfonso Bahillo, Ruben M. Lorenzo, Patricia Fernandez, Francisco A. Lago, Eduardo Garcia, Juan Blas, RobustIndoor Positioning Provided by Real-Time RSSI values in Unmodified WLAN networks, IEEE Journal 2009.[6]Land Mobile Radio Systems, Edward N. Singer, PTR Prentice Hall, 1994, p.196BIOGRAPHIES AND PHOTOGRAPHSVijay Rayar received B.E. degree in Electronics and Communication Engineering from KLE‘s College of Engineering and technology Belgaum and currently pursuing M.Tech in VLSI Design and Embedded Systems KLE Dr. M. S. Sheshgiri College of Engineering and technology, Belgaum. Research interests include wireless communication systems, wireless indoor propagation system design.。