Wireless sensor network and its Applications Free Essays

Introduction Wireless sensor networks use sensing techniques to gather information about a phenomenon and react to the events in a specified environment by the means of Sensors. These small, inexpensive, smart devices, which are connected through wireless links, provide unique opportunities for controlling and monitoring environments. Technically, a sensor translates the information from the physical world into signals and prepares them for analysis and processing. We will write a custom essay sample on Wireless sensor network and its Applications or any similar topic only for you Order Now The terms, Wireless Nodes, Sensor nodes and motes can be used interchangeably in different contexts. Here we refer to them as motes. Motes are typically produced in large quantities and are usually densely distributed in the network. Their size(or their components size) varies from macroscopic- scale to microscopic or even sometimes nanoscopic-scale. â€Å"Micro-sensors with on-board processing and wireless interfaces can be utilized to study and monitor a variety of phenomena and environments at close proximity.† A mote is consisted of four major components: Processing Unit: For data processing and â€Å"managing the procedures that make the motes collaborate with other nodes to carry out the assigned sensing tasks.† Sensing Unit: To sense the physical world and convert the data into digital signal ready for processing. Transceiver Unit: To provide the connection of nodes in the network. Power Unit: To supply energy for the device components. Based on the application, motes may have some additional components such as location finding system, mobilizer and power generator. These components should be put together in a way to fit in a small size module, be adaptive to different environments and consume as little power as possible. The components of a mote Figure is a representation of data acquisition about a phenomena (Process) in the real world which can be sensed by a sensor. The sensed signal needs often needs some changing in order to be processed (Signal Conditioning). For example in order to make the signal range appropriate for conversion some changes on signal magnitude is needed through signal amplification. Unwanted noise can also be removed through this stage. The analog signal is then transformed to digital signal by using ADC and is ready for further processing or storage. Data acquisition and actuation Applications: Wireless sensor networks can be used in places where wired systems cannot be deployed (e.g., a remote or dangerous area). It can also be used in commercial products to improve the performance or quality of them or provide convenience for their users. Sensor can sense many different variables such as: temperature, humidity, pressure and movement. They can sense an environment continuously or they can be event driven and sense an event when it occurs. Wireless sensor networks can support a wide range of applications. Battlefield surveillance, Bridge and highway monitoring, Earthquake detection, Habitat Monitoring, Health care, Industrial monitoring and control, Tracking wildfires, Traffic flow and surveillance, Video surveillance and Weather monitoring are few examples of its applications. Military Applications One of the first applications of sensor network was military sensing. WSN could be used for monitoring the critical equipment, vehicle or weapons to make sure they are in a proper condition. Terrains, paths and roads could be monitored to sense the presence of opposing forces. They also can be used to enhance the targeting system of ammunitions. Human teams can be replaced by sensor networks in places affected by biological and chemical warfare or incidents in order to perform nuclear reconnaissance and prevent humans to be exposed to radiations. Traffic surveillance Traffic surveillance is another example of WSN applications. Sensors are placed in predefined places to gather data and send it via wireless links to data centres for further processing. This data can be beneficial for statistical purposes such as vehicle count per day, the number of cars per lane and the average speed of vehicles. It can also be useful for real time applications such as traffic flow monitoring, incident reporting and managing the traffic lights in order to prevent heavy traffics. Real-time traffic flow control Medical Applications: Wireless sensor network benefits are being explored by many hospitals and medical centres around the world. As it can be seen in Figure sensors can be implanted in patient body or connected to him in order to collect information about his vital signs such as heart beat, blood pressure and oxygen level in blood. This information can be transferred patient’s medical record for future examinations and long-term inspections. It also can be displayed in real-time or alert physicians based on the sensor program in case of any sudden change in under-care patient condition. http://www.infotech.oulu.fi/Annual/2007/opme.html Realization of these various applications requires wireless ad hoc networking techniques. However they are not suitably designed for special features and applications of sensor networks. WSN vs. Mobile Adhoc Netoworks [12] Although there are lots of similarities between Mobile ad networks (MANET) and WSN for instance their lack of network infrastructure, use of multi-hop routing and wireless channel, there are some major differences to point out. Nodes in MANET are designed for human interaction such as laptop and PDAs, whereas in WSN motes are usually left unattended in remote or dangerous locations with the least possible interactions. In WSN â€Å"the topology of the network may change dynamically† due to node failure. It can happen because sometimes motes in some specific areas may be damaged and fail. In some network topologies motes have a sleep/awake cycle in order to save energy, so the topology needs to change when a mote is not available at a specific time. In WSN unlike MANETs the source of energy is limited and the nodes are sometimes left unattended in places where there is no access to them to change or recharge their batteries. â€Å"The range of communications is typically within a few meters and at low rates (some kilobits per second); there are typically a few kilobytes of memory and the processor may operate at speeds of only some megahertz.† Mote design and communication aspect of WSN is totally application dependent and changes based on different application requirements. Motes in some wireless sensor applications remain sleep for the most of their lifetime and transfer their information in a timely basis in order to save energy. So the traffic flow in the network is almost infrequent and delay time is usually higher than MANET networks. Overview of 802.15.4 1-http://www.ieee802.org/15/pub/TG4.html - IEEE 802.15 WPANâ„ ¢ Task Group 4 (TG4) 2-http://www.zigbee.org/Specifications.aspx a ZigBee Alliance the Official Website 3-http://www.eetimes.com/showArticle.jhtml?articleID=173600329 - EE Times: The global electronics engineering community The IEEE 802.15.4 and the Zigbee alliance have been working together in order to improve WSN efficiency, safety, security, reliability and convenience of this technology. IEEE 802.15.4 focuses on physical layer and MAC layer at the 868MHz (Europe), 915MHz (US) and 2.4GHz (worldwide) ISM bands whereas Zigbee alliances work on higher level protocols. â€Å"The IEEE 802.15 was chartered to investigate a low data rate solution with multi-month to multi-year battery life and very low complexity. It is operating in an unlicensed, international frequency band.† â€Å"Some of the characteristics of IEEE 802.15.4 include: Data rates of 250 kbps, 40 kbps, and 20 kbps CSMA-CA(Carrier sense multiple access with collision avoidance) channel access Fully handshaked protocol for transfer reliability Power management to ensure low power consumption 16 channels in the 2.4GHz ISM band, 10 channels in the 915MHz I and one channel in the 868MHz band.† â€Å"The ZigBee specification enhances the IEEE 802.15.4 standard by adding network and security layers and an application framework. From this foundation, Alliance developed standards, technically referred to as public application profiles, can be used to create a multi-vendor interoperable solutions. For custom application where interoperability is not required, manufacturers can create their own manufacturer specific profiles.† [2]Some of the characteristics of ZigBee include: Global operation in the 2.4GHz frequency band according to IEEE 802.15.4 Regional operation in the 915Mhz (Americas) and 868Mhz (Europe). Frequency agile solution operating over 16 channels in the 2.4GHz frequency Incorporates power saving mechanisms for all device classes [802]IEEE 802.15.4 standard defines PHY (physical layer) and MAC (medium access control) layer for the purpose of low data rate wireless communications which consume very low power. Physical Layer Some of the main characteristics of the PHY are the processes of sensing the environment, turning on/off the transceiver, estimating the receiver power/link quality indication and transmitting/receiving the information between two nodes. It finally sends the result of channel assessment to the MAC layer. The PHY is responsible for providing two services: PHY Data Service: â€Å"Enables the transmission and reception of PHY protocol data units (PPDUs) across the physical radio channel. PHY management service There are different frequency bands and data rates which a device should be able to operate with which are summarized in Table ?. Table – Frequency bands and data rates Mac Layer MAC layer provides access to the physical radio channel to transmit MAC frames. Some of the main characteristics of MAC sublayer are network beaconing, frame validation, Guarantees time slots (GTS) and handles node associations. The MAC layer is responsible for providing two services: MAC Data Service: â€Å"Enables the transmission and reception of MAC protocol data units (MPDUs) across the PHY data service.† MAC Management Service IEEE 802.15.4 MAC can work with both beacon enabled and non-beacon models. When it is on non-beacon model it is a simple CSMA/CA protocol but in beacon enable mode it works with super frame structure, shown in Fig. The frame starts with a Beacon which is sent by coordinator periodically. The frame also contains inactive period and active period. During the inactive period the device switches to low power mode and communicate with others during active period. The Beacon Interval is calculated based different attributes. In Active period the portion is divided into 16 slots which consist of three parts: Connection Access Period (CAP), Collision Free Period (CFP) (the GTS sections within it is for specific nodes) and the beacon. Fig Superframe structure Network Topologies ZigBee supports 3 types of topologies: Star, Mesh(peer-to-peer) and Cluster tree as shown in Fig . – Star topology: In this topology the communication is only between the single central controller called Personal Area Network (PAN) coordinator and other devices in the network which is mostly suitable for small networks such as single hop networks. A PAN coordinator usually has a unique identifier which is only used by this specific coordinator and allows different star networks to operate separately in the same area. – Mesh topology: This topology also has a PAN coordinator like Star topology but with the difference of having communication not only between coordinator and devices but between devices as well when they are in the range of one another. Although it makes the network structure more complex, but as a result of allowing multi-hop routing it is suitable for large networks. It also can be an adhoc network with self-healing and self-organizing characteristics. – Cluster tree topology: Cluster tree network is a form of peer-to-peer network. One coordinator operates as a PAN coordinator which has the responsibility of defining Cluster Heads (CH). The CH is a kind of Full Function Device (FFD) which can act as a coordinator. Each Reduced Function Device (RFD) then can selects its CH and joins that cluster. This kind of structure has a great impact on energy saving in the network which will be discussed later. Fig Topology Model Energy Conservation and measurement: [24]A wireless sensor network is created with hundreds or thousands of sensor motes, distributed independently in a remote area with the responsibility of sensing the environment, processing information and communicating with other motes in the network for years with a limited source of energy provided by a small battery which is almost impossible to be changed or recharged during motes life time. Therefore the concept of energy consumption management in the network has become one of the most important aspects of wireless sensor network design and implementation. The power saving approach has affected the mote design, power management strategies, communication and routing protocols of the WSN. Generally energy saving methods are divided in two major categories: Energy saving at Mote level; aims to selects the most energy efficient components of the device and trade off unnecessary operations in order to save energy based on the application requirements. Energy saving at Communication level; selecting the most efficient communication methods and protocols to conserve energy at this level. Power saving at mote level: The first step in saving energy at mote level is to find out where the energy is consumed in the mote. As it was mentioned before, a mote consists of 4 components: Processing Unit, Sensor, Transceiver and a Power supply to provide energy for the mentioned parts. Based on the experimental measurements in [40] data transmission is more energy consuming that data processing. Passive sensors such as temperature sensors on the other hand consume a small amount of power compared to other components which is almost usually negligible. Table shows a power model of a Mica2 mote in different states. How to cite Wireless sensor network and its Applications, Essay examples

Enjoyment of Being a Girl Overcoming Industry Sta Essay Example For Students

Enjoyment of Being a Girl: Overcoming Industry Sta Essay ndards Have you ever been looking at a magazine and notice you are not what a guy wants? Or have you ever sat and watched television and then proceeded to look into the mirror and feel so badly about your appearance that you felt depressed? Many women in todays world experience these same feelings each time they come in contact with some type of media. The media has always used women as a way to sell products or used them as propaganda, but how far is too far? The media is a large source of entertainment for women of today. Women spend the majority of their time looking at magazines for latest fashions or trends. These media sources all share one subject: negative images of women. These places all share one thing; negative images of women. Women are being used as a sex object and are not portrayed how the average woman looks. These portrayals can lead to loss of self-esteem and also weight loss. Women should know that they need their spiritual health to live happily and not be influenced by the images that the media portray as the perfect body. Women need to have a feeling of being safe, powerful and comfortable within their own bodies. Media has a negative impact on the way women feel about their bodies, says Julie Parsons a clinical social worker (WVU). The media is such a huge influence in peoples lives sometimes they dont realize it. As women are walking down the street, the media can influence them. As people are riding in the car, the media can influence them. And even as people are sitting in the comfort of their own home, the media can influence them. The media is everywhere influencing our lives; from television to magazines to the Internet (Medias Negative). As a woman grows older she often finds it difficult to be secure in her own body. America has a desirable standard that many women want and try to live up too (Medias not). This is why the media has so many young women that are extremely underweight for their height and bone structure. Weight and shape concerns are influenced by the media (Medias portrayal). This desirable standard has so many women feeling obese that women cannot think about themselves in a healthy way, which is an enormous problem. The culture of todays society is surrounded by looks. People in society believe they have to have the right car, the right cigarette, the right food, and the right attitude; all with the right body (Smith). But what society doesnt see is that 99% of women can never live up to the body type the media presents (Medias portrayal). It is as though the media is a bad demand out for no good because Americas standards are so unrealistic (Medias not). The media paints a picture of unrealistic body images that make people feel they dont fit and cant fit in, said Shelly Perlin a Sciences Major (WVU). Women come into the world with a sense of innocence and no worries and then once they reach a certain age, they start feeling a sense of security if they have what others have, or if they are the perfect women. Women have to face so many different standards within a short span of life that they do not always know what is right. The media is a major influence and influences society beyond its knowledge (Medias). The media is so influential that it does not allow people to make their own personal judgments (Medias ticket). Some people feel as though the media is not all to blame for negative body images. Television and Magazines have a high impact on women today. In television the majority of female characters on T.V. are thin (Medias not). Statistics show that the average adolescent girls unrealistic body images are due to the three to four hours of T. .udf7cd6c9efe5a199e1bb4650b73d3503 , .udf7cd6c9efe5a199e1bb4650b73d3503 .postImageUrl , .udf7cd6c9efe5a199e1bb4650b73d3503 .centered-text-area { min-height: 80px; position: relative; } .udf7cd6c9efe5a199e1bb4650b73d3503 , .udf7cd6c9efe5a199e1bb4650b73d3503:hover , .udf7cd6c9efe5a199e1bb4650b73d3503:visited , .udf7cd6c9efe5a199e1bb4650b73d3503:active { border:0!important; } .udf7cd6c9efe5a199e1bb4650b73d3503 .clearfix:after { content: ""; display: table; clear: both; } .udf7cd6c9efe5a199e1bb4650b73d3503 { display: block; transition: background-color 250ms; webkit-transition: background-color 250ms; width: 100%; opacity: 1; transition: opacity 250ms; webkit-transition: opacity 250ms; background-color: #95A5A6; } .udf7cd6c9efe5a199e1bb4650b73d3503:active , .udf7cd6c9efe5a199e1bb4650b73d3503:hover { opacity: 1; transition: opacity 250ms; webkit-transition: opacity 250ms; background-color: #2C3E50; } .udf7cd6c9efe5a199e1bb4650b73d3503 .centered-text-area { width: 100%; position: relative ; } .udf7cd6c9efe5a199e1bb4650b73d3503 .ctaText { border-bottom: 0 solid #fff; color: #2980B9; font-size: 16px; font-weight: bold; margin: 0; padding: 0; text-decoration: underline; } .udf7cd6c9efe5a199e1bb4650b73d3503 .postTitle { color: #FFFFFF; font-size: 16px; font-weight: 600; margin: 0; padding: 0; width: 100%; } .udf7cd6c9efe5a199e1bb4650b73d3503 .ctaButton { background-color: #7F8C8D!important; color: #2980B9; border: none; border-radius: 3px; box-shadow: none; font-size: 14px; font-weight: bold; line-height: 26px; moz-border-radius: 3px; text-align: center; text-decoration: none; text-shadow: none; width: 80px; min-height: 80px; background: url(https://artscolumbia.org/wp-content/plugins/intelly-related-posts/assets/images/simple-arrow.png)no-repeat; position: absolute; right: 0; top: 0; } .udf7cd6c9efe5a199e1bb4650b73d3503:hover .ctaButton { background-color: #34495E!important; } .udf7cd6c9efe5a199e1bb4650b73d3503 .centered-text { display: table; height: 80px; padding-left : 18px; top: 0; } .udf7cd6c9efe5a199e1bb4650b73d3503 .udf7cd6c9efe5a199e1bb4650b73d3503-content { display: table-cell; margin: 0; padding: 0; padding-right: 108px; position: relative; vertical-align: middle; width: 100%; } .udf7cd6c9efe5a199e1bb4650b73d3503:after { content: ""; display: block; clear: both; } READ: Children And Art Therapy EssayV. they watch (WVU). After women watch at least thirty minutes of T.V. or advertisements with thin women, they show signs of guilt, depression, shame, and body dissatisfaction (Medias Negative). According to the University of Missouri-Columbia studies, the average woman that becomes so .

China intentions Essay Example For Students

China intentions Essay Osama bin Laden has done Communist China a favor. Because the minds of President Bush and congressional leaders are so concentrated on the war on terrorism, they have all but ignored Beijings aggressive military buildup. A strong possibility exists that by focusing so closely on Iraq, a focus that is understandable considering how unsettled the situation is, the United States could miss developments that could affect its standing in the rest of the world. Among the many uncertainties of the Asian security environment, none is more compelling than that surrounding the modernization program of the Chinese Peoples Liberation Army. For some observers, the combination of economic growth and force improvement signals Beijings intention to establish regional supremacy. Others acknowledge that the PLA can spoil the United States interests; however, Beijings interest in regional stability, and the growing conventional capabilities of other regional powers, they tend to discount a PLA military threat. Chinese secrecy compounds the difficulty. Chinas armed forces may not be a direct threat to the United States, but are good enough to cause plenty of trouble in their region and will be better in the future. China is one of the few nations to increase its defense spending in the post cold-war world, and is engaged in a major effort to upgrade its weapons capability for a possible quick strike on Taiwan. Taiwan would face an enormous challenge in r epelling a determined Chinese attack. The island is too close to the mainland and too inferior in forces to hold out indefinitely. Its technological advantages would enable it to prolong the struggle, but not defeat China. If the United States were to get involved, it would face a nuclear-armed adversary capable of striking its American shores. That is not likely to happen, but it has to be kept in mind. China has greater military power today than it did a decade ago. If Beijing were willing to pay the price, the PLA could wreak great damage. In assessing Chinas future threat potential, it is essential to consider the economic, political, and strategic constraints on PLA modernization. Such considerations suggest that the PLA is years away from achieving the capability to project military force in a sustained manner. Chinas likely future strategic intentions can be difficult to predict and there are many theories put forth by many different experts. Defense budgets can be a useful, even a critical, indicator of national defense priorities, policies, strategies, and capabilities. The size of a countrys defense budget, the rate of growth or decline in its military expenditures, and what it spends its defense dollars on can reveal much about a countrys strategic intentions and future military plans. Defense budgets can also be a good indicator of a countrys military modernization priori ties and therefore its possible future military capabilities. Finally, military expenditures can serve as a gauge of a nations defense commitment and resolve or its potential to threaten others. The PLA is developing six distinct types of fighters, more than any nation, and a new mobile strategic missile that Air Force Intelligence calls a significant threat to US forces in the Pacific and portions of the continental United States. Chinas recent weapons purchases from Russia comprise advanced warplanes, two guided-missile destroyers, and top-of-the-line artillery. The Office of Naval Intelligence reported that Beijings leaders are committed to deploying a 40,000-ton-class aircraft carrier by 2010. US defense officials are reluctant to openly characterize China as a threat, or even potential threat, but Chinas march to acquire sophisticated weapons, combined with a raft of troubling statements issued by Chinese military officials, has raised new concerns about the worlds most populous nation. The head of US Pacific Command, maintains that US forces are far superior to anything fielded by the Chinese PLA. However, he said he is under no illusions about the potential dangers th at a rearmed China could pose in another decade or so. China is also purchasing weapons from other countries to include the former Soviet Union; among Chinas new weapons are purchases from Russia, including guided missile destroyers and diesel-electric powered attack submarines that could threaten American warships. Outside experts on the Chinese military said it remained impossible to state with certainty Chinas military intentions. China could be preparing to challenge the United States and its allies, Asian or otherwise, for dominance of the Asia-Pacific region. China has expanded its national security objectives, has changed its patterns in the use of military force, is developing a modern war machine and sea control capability and, is attempting to build an anti-American and anti-West alliance. There can only be one reason for these activities. These are not moves directed at local opponents or guided by the principles of self-defense. This is a move aimed at the worlds sole re maining superpower, the United States. American world dominance rests on the fact that it is master of the North and South American continent, the oceans that surround that land mass, and a forward presence in strategically important regions of the world such as, Western Europe, the Persian Gulf, and Asia. If China and the PLA can marginalize the United States in Asia, then they can challenge the United States mantle as the worlds only superpower. Only time will tell if they can be successful in their ambition. .ud425ac44aaf8b52df96c1ea42a6ccd69 , .ud425ac44aaf8b52df96c1ea42a6ccd69 .postImageUrl , .ud425ac44aaf8b52df96c1ea42a6ccd69 .centered-text-area { min-height: 80px; position: relative; } .ud425ac44aaf8b52df96c1ea42a6ccd69 , .ud425ac44aaf8b52df96c1ea42a6ccd69:hover , .ud425ac44aaf8b52df96c1ea42a6ccd69:visited , .ud425ac44aaf8b52df96c1ea42a6ccd69:active { border:0!important; } .ud425ac44aaf8b52df96c1ea42a6ccd69 .clearfix:after { content: ""; display: table; clear: both; } .ud425ac44aaf8b52df96c1ea42a6ccd69 { display: block; transition: background-color 250ms; webkit-transition: background-color 250ms; width: 100%; opacity: 1; transition: opacity 250ms; webkit-transition: opacity 250ms; background-color: #95A5A6; } .ud425ac44aaf8b52df96c1ea42a6ccd69:active , .ud425ac44aaf8b52df96c1ea42a6ccd69:hover { opacity: 1; transition: opacity 250ms; webkit-transition: opacity 250ms; background-color: #2C3E50; } .ud425ac44aaf8b52df96c1ea42a6ccd69 .centered-text-area { width: 100%; position: relative ; } .ud425ac44aaf8b52df96c1ea42a6ccd69 .ctaText { border-bottom: 0 solid #fff; color: #2980B9; font-size: 16px; font-weight: bold; margin: 0; padding: 0; text-decoration: underline; } .ud425ac44aaf8b52df96c1ea42a6ccd69 .postTitle { color: #FFFFFF; font-size: 16px; font-weight: 600; margin: 0; padding: 0; width: 100%; } .ud425ac44aaf8b52df96c1ea42a6ccd69 .ctaButton { background-color: #7F8C8D!important; color: #2980B9; border: none; border-radius: 3px; box-shadow: none; font-size: 14px; font-weight: bold; line-height: 26px; moz-border-radius: 3px; text-align: center; text-decoration: none; text-shadow: none; width: 80px; min-height: 80px; background: url(https://artscolumbia.org/wp-content/plugins/intelly-related-posts/assets/images/simple-arrow.png)no-repeat; position: absolute; right: 0; top: 0; } .ud425ac44aaf8b52df96c1ea42a6ccd69:hover .ctaButton { background-color: #34495E!important; } .ud425ac44aaf8b52df96c1ea42a6ccd69 .centered-text { display: table; height: 80px; padding-left : 18px; top: 0; } .ud425ac44aaf8b52df96c1ea42a6ccd69 .ud425ac44aaf8b52df96c1ea42a6ccd69-content { display: table-cell; margin: 0; padding: 0; padding-right: 108px; position: relative; vertical-align: middle; width: 100%; } .ud425ac44aaf8b52df96c1ea42a6ccd69:after { content: ""; display: block; clear: both; } READ: Bacteria Classification By Gram Staining Essay.

Motion Down a Slope Essay Example

Motion Down a Slope Essay There are a number of things that affect the acceleration of the marble:- Angle/Gradient of slope. Changing the angle of the slope would affect the acceleration of the squash ball as it changes the energy the marble starts with as steeper angles raise the slope start higher so the marble would have more potential energy.- Mass of marble. Changing the mass of the marble would affect the acceleration because it means it has more energy pulling it downwards and so would accelerate faster.- Surface. Changing the surface may change the amount of friction between the slope and the marble. This would affect the amount of energy absorbed. If there was more friction then more energy is absorbed so the marble has less pushing it along and so accelerates slower.- Gravity. A change in the gravity would change the amount of energy pulling down the marble and so change the amount of energy pushing it along and so change the acceleration of the marble.- Aerodynamics. A change in the aerodynamics wo uld create a change in the air friction. This would change the amount of energy absorbed and so change the amount of energy left pushing it along changing the acceleration.I am going to investigate the angle of slope. The other variables must be kept the same. I will use the same marble so that the aerodynamics and mass of the marble stay the same. I will do the experiment in the same place every time and on the same slope so that the gravity and friction will remain relatively constant. This makes the investigation a fairer test.Measuring Acceleration:Acceleration cannot be measured directly. It has to be derived from other measurements. The measurements required are starting speed, distance and time.I will use the formula: S=UT+0.5AT2S = Distance (m) S=0T+0.5AT2U = Initial speed=0 every time S=0.5AT2T = Time (sec) 2S=AT2A = Acceleration 2S/T2=AA=2S/T2Method:Set up the equipment as shown above. Place the marble at the top of the slope. Start the stopwatch at the same time as you re lease the marble and then stop the watch when it reaches the end. Do this 3 times and take the average speed to try to remove anomalous results. Repeat with the slope at: 10o, 20 o, 30 o, 40 o, 50 o, 60 o, 70 o, 80 o, and 90 o.Use the formula: Sin (Angle needed) x Lengthto find the height the slope must be to make it the required angle. This will make the angles more accurate.Heights of top of slopes for required angles:10 o = Sin 10 x 150 = 26cm 20 o = Sin 20 x 150 = 51cm30 o = Sin 30 x 150 = 75cm 40 o = Sin 40 x 150 = 96cm50 o = Sin 50 x 150 = 115cm 60 o = Sin 60 x 150 = 130cm70 o = Sin 70 x 150 = 141cm 80 o = Sin 80 x 150 = 148cm90 o = Sin 90 x 150 = 150cmSafety Issues:There are no safety issues involved in this experiment.Prediction:I predict that the steeper the slope the faster the acceleration. This is because the steeper the angle the higher the marble starts and so the more potential energy it has. More potential energy means that when it is released it will have more kinet ic energy and so can accelerate quicker. Also the steeper the slope the less the marble is being pushed into the slope by gravity so there is less friction between the marble and slope.9.81 x Sin angle = Acceleration9.81 x Sin 90 = Acceleration9.81 x 1 = 9.81m/sI also predict, using the formula above, that the marble will not accelerate faster than 9.81m/s. This is the maximum acceleration of the marble. This is due to the fact that this is the acceleration is if the marble was dropped 150cm at 90? without any frictional or rotational effects. As we are working with friction the marble should always be slower. As the angles get nearer 90? the acceleration should begin to level off. This is because the later angles will not raise the height of the board and marble as much as the earlier angles so the marble will not be getting such a high increase in energy towards 90?. I predict that the formula 9.81 x Sin angle = Acceleration gives the exact acceleration of the marble.I predict my graph will look like this:This is because the marbles acceleration is increasing as the slope angle rises and then it levels off before reaching 9.81m/s.Results:Angle of SlopeHeight of Slope(cm)Time taken for marble to roll down slope (sec)(?)12345Average10261.481.501.491.511.491.4920511.141.121.111.101.161.1330751.091.141.121.110.971.0940960.620.690.680.660.630.66501150.610.670.680.690.630.66601300.600.600.660.610.610.61701410.510.540.550.560.560.54801480.560.570.580.560.580.57901500.550.560.560.570.590.57Acceleration:To work out the acceleration use the formula:A=2S/T2Angle of SlopeAverage TimeAcceleration(m/s)(?)(sec)101.491.35201.132.34301.092.52400.666.89500.666.89600.618.06700.5410.28800.579.23900.579.23Analysis:My prediction was correct with a few off measurements. The steeper the slope the faster the acceleration. So the angle of the slope is proportional to the acceleration, but it is not directly proportional. The graph had the same basic shape as my prediction, but again there were a few off points. The graph has a curved, best-fit line, which proves the angle, and the acceleration are proportional.I had three main anomalous results. These angles were; 30?, 40? and 70?. I rectified these by repeating the angles.These were my new results:Angle of SlopeAcceleration(m/s)Time taken for marble to roll down slope (sec)(?)12345Average303.001.011.030.961.060.931.00405.060.750.790.770.740.790.77708.920.590.610.560.560.560.58I can now compare my set of results to the theoretical set of results, which I found using the formula: 9.81 x Sin angle = AccelerationThe calculated data is:10 o = 9.81 x Sin 10 = 1.70m/s 20 o = 9.81 x Sin 20 = 3.55m/s30 o = 9.81 x Sin 30 = 4.91m/s 40 o = 9.81 x Sin 40 = 6.31m/s50 o = 9.81 x Sin 50 = 7.51m/s 60 o = 9.81 x Sin 60 = 8.50m/s70 o = 9.81 x Sin 70 = 9.22m/s 80 o = 9.81 x Sin 80 = 9.66m/s90 o = 9.81 x Sin 90 = 9.81m/sThe new graph is as I predicted and shows my data follows the same basic curve as the theoretical results. Howev er all of my data is slower accelerating than the theoretical set. This is because the theoretical set ignores friction. As the marble is not perfectly spherical it often left contact with the table. This could have prevented the marble rolling in a straight line. This means my results have also experienced rotational effects as they rolled whereas the theoretical results ignored this. The frictional and rotational effects would have absorbed energy from the marble causing it to be slowed down. This means the marble in my experiment could not have accelerated as quickly as the calculated results show.From this I can conclude that the steeper the slope the faster the acceleration. Also that the formula to find the theoretical data works and the theoretical data shows the acceleration of an object rolling down a slope with none of its energy lost.Evaluation:The data I collected was quite good and follows the same basic pattern as the theoretical data. My original results were not very accurate, especially drop height 30?, 40? and 70?. However, these were redone and now are greatly improved. 30? is still slightly anomalous. Despite this I feel my results are sufficiently reliable to support the conclusion that the theoretical data shows the acceleration down a slope where there is no energy lost from the object.I feel the reason for the inaccuracy could be because the marble was not perfectly round meaning it did not roll in a completely straight line and that it changed the friction. It could also be that the slope was not set at exactly the right height or angle. Another more major reason could be that the time was not measured correctly or accurately. Measuring the time by hand and eye caused many problems. This meant the results could never be very accurate. The clock could not be started exactly as the ball was released. Also the eye could not see exactly when the marble reached the end and the clock could not be stopped quick enough.To improve the experimen t and the quality of the data you could get a computer to measure the time taken. There could be a clamp, meaning the ball is released exactly as the time is started. Also using lasers could mean the timer was stopped exactly as the marble reaches the end. This would make it a lot more accurate. The computer could also set the angle of the slope perfectly. Also you could increase the number of times taken at each angle to get a better average and cut down anomalous results even more.My results suggest that the theoretical data was correct, as mine where only slower due to friction, and they support the conclusion. Further investigation could be done to help support this. For example, using a perfectly round ball such as a metal ball bearing, and a smooth metal slope. This would remove some of the friction and get closer results to the theoretical set. Also for further work the marble could be rolled down different texture slopes to investigate the effects of varying amounts of frict ion. This would provide additional information, which would help identify exactly how much friction does affect the results, compared to the theoretical set.To extend the investigation you could do the same experiment but keep the slope at the same angle and change the mass of the ball. This would investigate how the mass effects the acceleration.

On Being Tentative

On Being Tentative If you are afraid to write, then dont. If you are afraid to submit, then dont. If you are afraid to publish, then dont. Youre getting in the way of the glut of writers out there whove decided fear is not an option. I get riled at many programs, classes, and blog posts that tell you magically how to overcome fear, how to make yourself do any of the writing tasks required of a serious writer. If a writer has to pay someone else to remove that fear, then chances are that fear will return after payment has been rendered and the writer is left alone again. In other words, when the crutch is gone, the writer flounders again, seeking someone, something, some entity that will prop him up again and hold his hand to the finish line. When the motivation ought to organically come from within. Im not making light of the fear involved in this profession. We bare our hearts and souls to strangers then hold our arms open for the potential lashing. Yes, its hard. Everything that tests us, challenges us, or strengthens us is an obstacle, and in the end, we are the only ones that can decide to dig in, overcome,  and make it happen. So when I see the titles that say something like How to get over the fear of publishing, . . . I get mad. The lone writer is the only soul who can fix fear. Learn a lesson, tuck it into your tool box, and move on. Reach inside yourself and make your own decision to improve, submit, publish. At the end of the day, you are the only one left standing to make the decision on where to take your writing. This job is lonely. The only way you can get inside your head and tap those luscious words that sell is to be alone, edit alone, submit alone. You make the choices. You make the changes. You make the long-term decision to stick this crap out and make it happen. At the moment I hear a hundred voices shouting But followed While this editorial might raise the blood pressure of a few readers, so be it. Face reality. Writing is not a group effort. Sure, you hire people or sign contracts with others along the way, even thinking an agent is your life vest, but the bottom line is that you pen the words. This is all on you. We all like the pat on the back and the positive reinforcement. Thats human nature. But if you need someone  petting you on the head every day to keep going, maybe this isnt the job for you. There are too many others out there who show up everyday to make their dream happen. And they left their mommas in the other room.

Dealing with a Nuclear Iran Essay Example | Topics and Well Written Essays - 2000 words

Dealing with a Nuclear Iran - Essay Example Thinkers such as LaFranchi (2006) as well as Carter (2006) have made it clear that some nations may be responsible enough to possess nuclear bombs but others may have to be prevented from gaining access to such technology. In this regard, nuclear proliferation becomes an international problem when countries such as Iran and North Korea generate different opinions on how they should be handled. While the case of North Korea is more or less settled, Iran remains and issue and there are several methods given by expert analysts which show that the nuclear intentions of Iran can be handled in several ways. The basic reason for why Iran is seeking nuclear armament is because Iran wants to make itself regionally secure. The need for security is reflected in the history of Iran since in 1941, the Allies wanted to find a path through the country to support the Russian front against Germany. The King of Iran, Reza Shah was suspicious of the motives of the allies and was thus removed from the throne. This was a basically a misunderstanding between the allies and the Iranian people but it turned them away from the allies in historical terms (Kilgore, 2007). The troubled history of Iran and the west continued through the revolution until in recent years, Bush made Iran a part of the ‘Axis of Evil’. In these circumstances, Iran can clearly see that America does not attack a nuclear capable North Korea while it continually threatens a non-nuclear Iran (Kilgore, 2007). Iran wants to avoid the fate of Iraq which was attacked for allegations of having weapons of mass destruction while it had none (Jackson, 2006). The false charges brought by the American government caused the Iraqi people a lot of misery and even though Saddam was a cruel ruler, the methods used to remove him and the timing was less than ideal (Kilgore, 2007). In fact, Kilgore (2007) suggests that it is the manipulation of the Israeli lobby which is causing fingers to

Chinese New Year Essay Example | Topics and Well Written Essays - 750 words

Chinese New Year - Essay Example I hope you would not ask me how this system works because aside from possibly taking me more than 60 minutes of your time, I am sure that the explanation would all put you to sleep. The purpose of my narrative discourse is to illumine your thoughts on the disparity of how we normally celebrate Chinese New Year from what I have observed during my stay in the United States. This year, Chinese New Year was celebrated last January 23 and has been marked as the year of the Water Dragon. We believe that in preparation for the New Year, all family members must participate in the event by observing old traditions and practices. We believe that to bring in good luck, our family must take out all old and dirty things by cleaning every nook and corner of the house and to bring out bad luck during the previous year. We observe placing specific decorations that include posting popular characters or symbols such as Luck, Money, Wealth, Happiness, Prosperity or Health on a diamond-shape red paper a nd paste them on the doors, windows, and money safety boxes. The best thing I enjoy during Chinese New Year is the dishes that are prepared for the celebration. There are also specific meanings for the foods that are prepared. For example, mother cooks meat dumplings for good luck; sweet rice cakes for more wealth every year; fish for plenty; vegetables with long noodles for long life; chicken for wealth; soup means everything better than last year; and shrimp for abundance. We also ensure that specific fruits are on the dining table, also with distinct meanings: tangerines for good fortune; apples for peace; orange for money and wealth. I sometimes think that the Westerners’ preparation for a bowl of fruit cocktail would be better to attract prosperity and good luck. Another custom that we never forget is giving Hong Bao which is a red envelope that contains brand new money. Parents and grandparents give Hong Bao to children and relatives also to signify good luck and prospe rity. In China, there are festivities that include watching dragon dances and paying our respects to our ancestors through offering foods and incense. While in the United States, we still get to pay our respects through observing adherence to these customs and traditions. I actually miss waiting patiently in vigil for the coming of the New Year, especially in locations where it is welcomed through a magnificent display of fireworks. The value of adhering to old traditions could not be ignored as they form an important part of one’s life. The way we celebrate New Year in China could be significantly different from the way New Year celebration is practiced in the United States. The disparity was eminent in distinct practices of warding off bad luck through age old traditions of cleaning, preparing selected foods and fruits, and giving away tokens for good fortune. Despite the differences, I admit that where ever and how ever people celebrate New Year, the important thing we re alize is that it is a time to leave our bad practices and mistakes and learn to move on with steadfast determination to do good in words and actions towards our fellow men. After reminiscing, I realize that I am most fortunate to have the opportunity of celebrating two New Years’ festivities every single year - I must have been and would still be the recipient of double doses of prosperity and go