Heat Detector Essay Example for Free

Heat Detector Essay When present, humans can be excellent fire detectors. The healthy person is able to sense multiple aspects of a fire including the heat, flames, smoke, and odors. For this reason, most fire alarm systems are designed with one or more manual alarm activation devices to be used by the person who discovers a fire. Unfortunately, a person can also be an unreliable detection method since they may not be present when a fire starts, may not raise an alarm in an effective manner, or may not be in perfect heath to recognize fire signatures. It is for this reason that a variety of automatic fire detectors have been developed. Automatic detectors are meant to imitate one or more of the human senses of touch, smell or sight. Thermal detectors are similar to our ability to identify high temperatures. The properly selected and installed automatic detector can be a highly reliable fire sensor. Our automatic fire alarm system is designed to detect the unwanted presence of fire by monitoring environmental changes associated with combustion. In general, our fire alarm system is classified as either automatically actuated, manually actuated, or both. Automatic fire alarm systems are intended to notify the building occupants to evacuate in the event of a fire or other emergency, report the event to an off-premises location in order to summon emergency services, and to prepare the structure and associated systems to control the spread of fire and smoke. Whenever the system detects a high temperature, the fire alarm will inform the area and send a text message to the fire station and will inform them the specific block/area in the subdivision which is on fire. GSM/GPRS module is used to establish communication between a computer and a GSM-GPRS system. Global System for Mobile communication (GSM) is an architecture used for mobile communication in most of the countries. In our system, we will be using GSM modem Nokia 6300 for the output of text. The device will send a text message to the nearest fire station and will inform which house is on fire. Control Panel The control panel is the brain of the fire detection and alarm system. It is responsible for monitoring the various alarm input devices such as manual and automatic detection components, and then activating alarm output devices such as horns, bells, warning lights, emergency telephone dialers, and building controls. Control panels may range from simple units with a single input and output zone, to complex computer driven systems that monitor several buildings over an entire campus. Upon fire occurrence, one or more detectors will operate. This action closes the circuit, which the fire control panel recognizes as an emergency condition. The panel will then activate one or more signaling circuits to sound building alarms and summon emergency help. The panel may also send the signal to another alarm panel so that it can be monitored from a remote point. Alarm Output Devices Upon receiving an alarm notification, the fire alarm control panel must now tell someone that an emergency is underway. This is the primary function of the alarm output aspect of a system. Occupant signalling components include various audible and visual alerting components, and are the primary alarm output devices. All fire alarm systems require notification devices, including sirens, bells, horns, and/or strobes. In residential applications, each automatic alarm initiating device when activated shall cause the operation of an alarm notification device that shall be clearly audible in all bedrooms over ambient or background noise levels (at least 15dB above noise) with all intervening doors closed. Bells are the most common and familiar alarm sounding device, and are appropriate for most building applications. Horns are another option, and are especially well suited to areas where a loud signal is needed such as library stacks, and architecturally sensitive buildings where devices n eed partial concealment. In this case, we will be using Siren as the alarm output device. Some of the major benefits of installation of fire alarms are as follows. †¢ Safety is the most important reason why we should have fire alarms in our house, even before a fire breaks out, the smoke detectors tell you there is a possibility of a fire and you can safely be out of danger. Secondly being pre informed about a possible fire, a prompt message can be conveyed to the fire workers. As a result of this, damage can be minimized and valuables can be saved from being burnt to ashes. †¢ A house with a fire alarm is a safer house and fetches a far better price in the real estate market. The customers feel secured when they see that they are opting for a property that has the safety measures installed. †¢ Using a fire alarm is a cost effective way to ensure that your assets are not in danger. Being noted beforehand you can move them out quickly thus saving your valuables from being burnt. †¢ The alarm works even when nobody is in the house and thus alerts the neighbours. This way your home can be protected from any major damages. Limitations of our Heat Sensor †¢ Heat detectors do not sense particles of combustion and are designed to alarm only when heat on their sensors increase at a predetermined rate or reaches a predetermined level. Heat detectors are designed to protect property, not life. †¢ Warning devices (including horns, sirens, and bells) may not alert people or wake up sleepers who are located on the other side of closed or partially open doors. A warning device that activates on a different floor or level of a dwelling or structure is less likely to awaken or alert people. Even persons who are awake may not notice the warning if the alarm is muffled by noise from a stereo, radio, air conditioner or other appliance, or by passing traffic. Audible warning devices may not alert the hearing-impaired (strobes or other devices should be provided to warn these people). Any warning device may fail to alert people with a disability, deep sleepers, people who have recently used alcohol or drugs, or people on medication or sleeping pills. Temperature Sensor The Thermistor Thermistors are temperature sensitive resistors. All resistors vary with temperature, but thermistors are constructed of semiconductor material with a resistivity that is especially sensitive to temperature. However, unlike most other resistive devices, the resistance of a thermistor decreases with increasing temperature. Thats due to the properties of the semiconductor material that the thermistor is made from. A Thermistor is a temperature dependent resistor. When temperature changes, the resistance of the thermistor changes in a predictable way. Sensor Advantages and Disadvantages [pic] Each sensor type has advantages and disadvantages. For thermistors, the major advantages are: Sensitivity: This allows thermistors to sense very small changes in temperature. Accuracy: Thermistors offer both high absolute accuracy and interchangeability. Cost: For the high performance they offer, thermistors are very cost-effective. Ruggedness: Because of their construction, thermistors are very rugged. Flexibility: Thermistors can be configured into a wide variety of physical forms, including very small packages. Hermetic Seal: Glass encapsulation provides a hermetic package, eliminating moisture induced sensor failure. Surface Mount: A wide range of sizes and resistance tolerances are available. Of the thermistor disadvantages, typically only self-heating is a design consideration. Proper care must be taken to limit the sensing current to a low enough value that self-heat error is minimized to an acceptable value. Types of Thermistors Thermistor Elements The thermistor element is the simplest form of thermistor. Because of their compact size, thermistor elements are commonly used when space is very limited. OMEGA offers a wide variety of thermistor elements which vary not only in form factor but also in their resistance versus temperature characteristics. Since thermistors are non-linear, the instrument used to read the temperature must linearize the reading. Linear Response Thermistor Elements For applications requiring thermistors with linear response to temperature change, OMEGA offers linear components. These unique devices consist of a thermistor composite for temperature sensing and an external resistor composite for linearizing. Thermistor Probes The standalone thermistor element is relatively fragile and cannot be placed in a rugged environment. OMEGA offers thermistor probes which are thermistor elements embedded in metal tubes. Thermistor probes are much more suitable for industrial environments than thermistor elements. Resistance Temperature Detector (RTD) RTDs (Resistive Temperature Detectors) serve as the standard for precision temperature measurements due to their excellent repeatability and stability characteristics. RTDs provide the designer with an absolute result that is fairly linear over temperature. The RTD’s linear relationship between resistance and temperature simplifies the implementation of signal conditioning circuitry. The RTD requires external current excitation, as well as signal conditioning to account for lead wire effects and self-heating. Analog Devices supplies the ADT70, which provides both excitation and signal conditioning for a platinum RTD. The output of this device (5 mv/ °C) is be fed through an analog to digital converter, to be converted by the DSP to temperature readings.

Personal Success, Seizures, Depression And Suicide :: essays research papers

Before the age of 15, I was as healthy as anyone could wish to be. In my sophomore year of high school, though, my seizures began. Nobody knew what they were at first; they looked as if I was passing out. These â€Å"episodes† as my mom and I were calling them, were finally defined as seizures when a nurse at the hospital saw that during one of my â€Å"episodes† I would clench my jaw shut and my muscles would tighten and shake. Doctors put me on three different medications over the next few years. The first , Dilanton, did nothing for me. The second, Tegratoal, was killing my white blood cells which made me extremely sick. The third , Depekot, worked, but with it came some nasty side affects, and I was still having seizures two to three times a week. I became depressed after a year of having seizures and being told by many doctors that they didn’t know what was causing it. The doctors also didn’t know how to treat it. I missed a lot of school my sophomore and junior year, which was why my grades weren’t what I wanted them to be. My teachers harped at me about not getting my work done. They didn’t understand. I also got a lot of strange looks from people when I walked down the hall. Most of my seizures happened during school. I can’t be positive about when my depression began to reach a climax. Maybe it was when my mom and her boyfriend would yell and scream at each other about how they were going to pay for all the hospital expenses. Or maybe it was all those nights lying in bed listening to my mom cry. Whatever the reason(s), I developed the mindset that I was causing my family all this pain, that it was my fault, I would never get into college, so it would be best if I wasn't around anymore. I felt other no emotion except sadness. I felt as if I were walking in a different dimension. I could see and hear people, but nothing anyone said made any difference to me. Nothing seemed to matter anymore. The world no longer had any color in it; it was all black and white; this is what I saw. I thought about how much better life would be for everyone if I were gone.

Conflict Theorists

Conflict theory was developed from the concern that the structural functionalism theory neglected conflict in society and was politically conservative. This conflict theory also addressed the perceived failure of structural functionalism to account for change in society (Ritzer, 1992, p. 61). This theory has evolved to include elements of structural functionalism and traditional Marxist focus on dominant and subordinate groups.Conflict theory often depicts a: polarization of the forces of â€Å"law and order† on the one hand and left wing political activists and minority group members reacting to what they saw as excessive police repression of political protests and urban riots on the other (Giffen, et al. , 1991, pp. 8-9) This aspect of conflict theory assumes, however, that the dominant and subordinate groups are more or less homogenous in nature.Most research in the field of drug policy recently, however, deals with power being located in â€Å"institutional structures in society such as economic, governmental and religious institutions (Giffen, et al. 1991, p. 10)† that do not presuppose homogenous groups. An example of this would be the comment of Riley after attending a conference on drug issues in the United States, where he remarked that â€Å"many researchers felt the real reason for the war on drugs in that country was that it helped to suppress blacks and minorities. (Riley 1994b)† One of the failings of conflict theory becomes apparent when researchers in the history of this legislation find little in the actual discussion of the laws that pertains to race.Giffen, et al. (1991) write that the early legislation's principle proponents had the â€Å"altruistic aims of supporting the international anti-opium movement† despite the anti-Chinese sentiment of the times (p. 525). The fact that the laws were used solely against the Chinese at first is indicative of this anti-Chinese sentiment, and not the creation of the laws thems elves. Later legislation was driven mainly by enforcement officials, as there was little in the way of public outcry for more rigorous anti-opium legislation (p. 525).Johns (1991) under the heading â€Å"Race: The Creation of an Enemy Class,† writes bluntly: â€Å"The enforcement tactics of the War on Drugs are focused on minority populations† (p. 155). In her paper, Johns (1991) posits that the War on Drugs takes attention away from the factors which underlie the problems of drugs and trafficking, partly because the â€Å"more powerful segments in society† (p. 150) do not want attention focused the poor job they are doing to cure the ills of society. Johns also expands the group being oppressed to include the poor, who have been hit with massive housing and health care cuts under the Republican Presidencies.The dichotomy between those in power and minorities and the poor is self-perpetuating, in that these groups have a limited upward mobility (and, therefore c rimes like trafficking in illicit drugs becomes appealing), and when they do try to increase their wealth through illicit means, those in power see that as justification for minorities and the poor being in the position they are in. The conflict theory is problematic in describing why there is a war on drugs. It may help to explain (as Johns (1991) successfully does) why a War on Drugs continues in the U. S. , but leaves unanswered questions when applied to other situations.

Comparison Between Friedrich Nietzsche And Dr. Martin...

Whether or not you agree with their views, both Friedrich Nietzsche and Dr. Martin Luther King, Jr. were great, highly influential men. Their views, though radically different, impacted the world in the greatest of ways, altering history for many nations. While Nietzsche, a German philosopher from the 1800s, spoke from a materialistic point of view, believing that there is no god and that all that exists is matter, King, a civil rights activist of the 1900s, spoke from the belief in transcendence, that there is indeed a god, and that he exists in a divine realm outside of this universe. But not only do these men differ in their backgrounds and religious beliefs, they differ radically in how they believe society should function. In Nietzsche’s writings, he promoted a system that emphasizes will to power. He believed that an aristocracy was the basis for a great society. King, on the other hand, promoted a system of equality and justice. He thought all men were created equal, an d that society should reflect that belief. The writings of these men have come to be studied by people everywhere. They are so influential, in fact, that one of them played an incredible role in getting our society to the point that it is today. As stated previously, Nietzsche’s work was both great and highly influential. The Nazis even used his writings as a basis for their beliefs. Nietzsche believed that the greatest societies were always built upon the aristocratic system. Since he believed thereShow MoreRelatedStephen P. Robbins Timothy A. Judge (2011) Organizational Behaviour 15th Edition New Jersey: Prentice Hall393164 Words   |  1573 PagesPerception? 166 Factors That Influence Perception 167 165 Person Perception: Making Judgments About Others 168 Attribution Theory 168 †¢ Common Shortcuts in Judging Others 170 †¢ Specific Applications of Shortcuts in Organizations 173 The Link Between Perception and Individual Decision Making 174 Decision Making in Organizations 175 The Rational Model, Bounded Rationality, and Intuition 175 †¢ Common Biases and Errors in Decision Making 177 Influences on Decision Making: Individual Differences and