...Bradford Hill * Conducted groundbreaking studies on cigarette smoking and lung cancer in the 1950s. * James Lind * Conducted one of the earliest experimental studies, which was the treatment of scurvy among sailors. * Using sound experimental principles, he found that the consumption of oranges and lemons were the most effective remedies for scurvy in this population. * William Farr * Compiled the Statistical Abstracts in Great Britain from 1839 through 1880. * He pioneered many activities encompassed by modern epidemiology, including the calculation of mortality rates using census data for denominators. Definitions * Epidemiology – the study of the distribution and determinants of disease frequency. It is an applied science whose primary mission is to identify targets for preventative interventions. It rests on two assumptions * Disease does NOT occur randomly * Causal and preventative factors can be identified through systematic investigation. * Essential Elements of the Epidemiologic Approach 1. Human participants 2. Systematic...
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...Operational amplifiers-OPAMP Ideal- characteristics Real- you buy LM741C Characteristics 1. AOL- Open loop gain – infinite (typical value 1000000 for LM741) 2. input resistance Rin=infinite(2Mohms) 3. input current = 0 4. Rout=0(small 75ohms) 5. AOLdoes not change with the frequency of the input signal- the voltage gain is constant VCVS-voltage controlled voltage source Negative feedback Lowers the voltage gain, and also makes it constant for a bigger range frequency INVERTING AMPLIFIER USING AN OP AMP Positive Vin negative Vout Negative Vinpositive Vout (1800 out of phase) Op amp with negative feedback will have ACL(closed-loop gain)—the new circuit (op amp +Rf+R)has a new gain which is called closed-loop gain Acl=-Rf/R Vout=-(Rf*Vin)/R; Rf>R The gain of the inverting depends on two resistors, Rf and R,Rf is connected between the output pin and inverting pin and Rf must be grater than the value of R. To have an amplifier, R is connected between the input signal and the inverting pin. The negative sign in the formula for the closed loop gain means that the input signal and the ouput signal are 180 out of phase, meaning that +inputs produce-output and vice versa. The output voltage cannot go above Vcc and Vee . The output wave is clip off wave’ The output wave will be a saw wave(triangular), if the gain is too much big. IR=IF+Iin (Iin=0) IR=IF Ir=Vin/R If=Vout/ Rf Vout/Vin=Rf/R To find the formula for ACL of inverting op amp amplifiers: ...
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...IR SPECTROSCOPY WITH INSTRUMENTATION BY MUHAMMAD ABDUL WAHAB ROL#428 Msc 2 SUBMITTED TO Dr.S.Mustansar Abbas IR SPECTROSCOPY It is the method or process to getting information about atoms and molecule by using electromagnetic radiation. OR The method of “seeing the unseenable”atoms and molecule. The field of spectroscopy related with internal structure of atom or molecule.There are different types of radiation but we use here IR RADIATION to analyte vibration change in electrons by IR Spectrum. INFRARED SPECTROSCOPY • IR Spectroscopy can be define as • The Study of concentration or specific obserption of infrared radiation which cause vibrational transition in the molecule. • IR light have longer wavelength and lower...
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...* DISPENSER * IR LEDS * SENSOR * INDICATOR * LAVATORIES * PHOTOTRANSISTOR * INFRARED * GALLIUM * ARSENIDE * PHOTORESISTOR(LDR) * RELAY * TELEGRAPH CIRCUIT * PROTECTIVE RELAY * IC BURNER DISPENSER One that dispenses or gives out, especially a machine or container that allows the contents to be removed and used in convenient or prescribed amounts. IR LEDS An IR LED, also known as IR transmitter, is a special purpose LED that transmits infrared rays in the range of 760 nm wavelength. Such LEDs are usually made of gallium arsenide or aluminium gallium arsenide. They, along with IR receivers, are commonly used as sensors. The appearance is same as a common LED. Since the human eye cannot see the infrared radiations, it is not possible for a person to identify whether the IR LED is working or not, unlike a common LED. To overcome this problem, the camera on a cellphone can be used. The camera can show us the IR rays being emanated from the IR LED in a circuit. SENSOR A sensor (also called detector) is a converter that measures a physical quantity and converts it into a signal which can be read by an observer or by an (today mostly electronic) instrument. For example, a mercury-in-glass thermometer converts the measured temperature into expansion and contraction of a liquid which can be read on a calibrated glass tube. A thermocouple converts temperature to an output voltage which can be read by a voltmeter. For accuracy...
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...Price-setting Behaviour – Insights from Australian Firms Anna Park, Vanessa Rayner and Patrick D’Arcy* Since 2004, the RBA has been conducting a survey of how firms set prices, how frequently they review and change prices, and what factors influence these decisions. the results show that firms employ a range of approaches to price setting, with around half reviewing their prices at a regular interval. early in the survey period, costs were the most important factor in price setting, though demand considerations became more important when economic conditions softened. Introduction The way firms set prices can be a key determinant of the dynamics of the inflation process. Given this, over recent years a number of central banks, including the Reserve Bank of Australia (RBA), have conducted surveys of how firms set prices, how frequently they review and change their prices, and what factors influence these decisions.1 This article discusses the results of an ongoing survey that has been conducted by the RBA since 2004. The main findings can be summarised as follows: • the surveyed firms employed a range of approaches to price setting, with slightly more setting prices as a mark-up on costs rather than in response to various demand factors; broadly the same number of surveyed firms reviewed prices at regular intervals (most commonly annually) as reviewed prices with each transaction or in response to external factors, although behaviour differs across sectors; and • costs...
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...Fourier Transform Infrared (FTIR) Spectroscopy Group 1 (Monday 1-5pm) Author Reshma Reji Outline Introduction Objective of the Experiment Theory * FTIR Spectroscopy * FTIR Spectrophotometer * Samples Experimental Physical properties of reagents used Solution Preparation Procedure Instrument settings Data 1. IR spectrum of Chloroform and D-chloroform 2. Rotational Spectrum of CO2 (Standard Resolution) 3. Rotational Spectrum of CO2 (High Resolution) 4. Carbonyl stretch in 2-butanone solutions (wavenumber vs. % T) 5. Carbonyl stretch in 2-butanone solutions (wavenumber Vs Absorbance) 6. Calibration curve of 2-butanone solutions (concentration vs. absorbance) * Calculations a. Preparation of solutions b. Concentration of the unknown c. Percent error of observed and theoretical ratios of CH, CD stretch frequencies Results and Conclusion References Objective The goal of the first part of the experiment was to study the effects of isotopes on bond stretching. In the second part of the experiment, the influence of instrument resolution on the rotational spectrum of carbon dioxide was studied. The purpose of the third part of the experiment was to create a calibration curve to find the unknown concentration of 2-butanone. Introduction Fourier Transform Infrared Spectroscopy (FTIR) is a very useful analytical technique used for qualitative and quantitative analysis of organic and inorganic...
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...Power Electronics 06EC73 POWER ELECTRONICS Subject Code: 06EC73 No. of Lecture Hrs/Week: 04 Total no. of Lecture Hrs: 52 IA Marks: 25 Exam Hours: 03 Exam Marks: 100 PART - A Introduction, Applications of power electronics, Power semiconductor devices, Control characteristics, Types of power electronics circuits, Peripheral effects. 5 Hours UNIT - 2 POWER TRANSISTOR: Power BJT’s, switching characteristics, Switching limits, Base derive control, Power MOSFET’s, switching characteristics, Gate drive, IGBT’s, Isolation of UNIT - 3 INTRODUCTION TO THYRISTORS: Principle of operation states anode-cathode characteristics, two transistor model. Turn-on Methods, Dynamic Turn-on and turn-off characteristics, Gate characteristics, Gate trigger circuits, di / dt and dv / dt protection, Thyristor firing circuits. 7 Hours CI TS UNIT - 4 CONTROLLED RECTIFIERS: Introduction, Principles of phase controlled converter operation, 1φ fully controlled converters, Duel converters, 1 φ semi converters (all converters 5 Hours with R & RL load). CITSTUDENTS.IN TU DE gate and base drives. NT S. IN UNIT - 1 6 Hours Page 1 Power Electronics 06EC73 PART –B UNIT - 5 COMMUTATION: Thyristor turn off methods, natural and forced commutation, self commutation, class A and class B types, Complementary commutation, auxiliary commutation, external pulse commutation, AC line commutation, numerical problems. 7 Hours UNIT - 6 AC VOLTAGE...
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...Detectors (PIR)convert the changes in incoming infrared light to electric signals. Pyroelectric materials are characterized by having spontaneous electric polarization, which is altered by temperature changes as infrared light illuminates the elements. Since our sensor series uses this effect they can be used at ambient temperature even in the presence of thermal noise. By choosing appropriate IR receiving electrodes, they serve a wide range of application. * Characteristics | High Sensitivity | | Versatile selection of IR wavelength filters | | Room temperature operation | | Low cost | | Roust under severe environmental conditions | | Stable against ambient temperature and atmospheric changes | | Stable against electromagnetic interference | * Applications | Light control | | Temperature measurement | | Flame detector | | Automatic door switch | | Visitor detector | | Home security | | | | | * IR Filters | AR coated silicon (low cost) | | 7µm cut-on, long pass, filtered silicon (body detection) | | 4.3 µm bandpass filtered quartz (flame detection) | | 4.5 µm AR coated silicon (body detection) | | 5µm cut-on silicon (body detection) | Relative transmittance of window. | | | | | Pyroelectric detectors are infrared...
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...|CM2101 (Principles of Spectroscopy) | |Experiment 1: Rovibrational Spectrum of Hydrogen Chloride | AIM To measure the infra-red (IR) spectrum of gaseous HCl using Fourier Transform Infra-Red (FTIR) spectrometer, and analyse the rotational fine structures. ABSTRACT The experiment aims to identify various parameters of gaseous HCl related to quantum mechanics by using high-resolution IR spectrum and graphical method of analysis. The values that are being investigated specifically are νe (equilibrium vibrational frequency), νeχe (product of equilibrium vibrational frequency and anharmonicity constant), k (force constant), B0 (rotational constant at n = 0), B1 (rotational constant at n = 1), Be (rotational constant at equilibrium internuclear distance), α (Coriolis constant) and re (equilibrium internuclear distance). The spectrum obtained shows strong fundamental absorption band approximately between 3100 and 2600 cm-1, with the origin of the band approximately at 2880 cm-1. It is also characterised by the presence of P and R branches which spreads out from the origin, with the former being present at a lower wavenumber region than the latter. In addition, double peaks are observed due to the presence of two isotopes of chlorine: 35Cl and 37Cl. INTRODUCTION One of the areas being...
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...--------- 4 Investor Targeting-------------------------------------------------------------- 5 The IR Programme------------------------------------------------------------ 7 Malaysian IR Organization-MIRA------------------------------------------ 8 Reference------------------------------------------------------------------------ 9 The definition of Investor Relations Nowadays, many companies show and market themselves to investors when they at the primal Public Offering stage through the prospectus which is managed by official requirements and ordinations. After listing, besides meeting the compulsive persistent disclosure requirements, many companies often draw their attention to communicating with investors, Annual Report and the AGM is the only method of communication. However, AGMs have been regarded as the most ineffective one, mainly due to poor attendance, time limited, logistical problems and their lack of frequency. In an age that “instant corporate information” can be delivered to an international audience by the internet, if the companies do not engage with investors, on a continuous basis will lack visibility. Investors have so many choices, PLCs which do not have an IR programme will be short of coverage and support. This will leads to illiquidity of the stocks, poor valuation and unhappy stakeholders at last. The IR challenge is to protect investors’ interest not only by publishing...
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...INFRARED METHODS ´ JANA MADEJOVA AND PETER KOMADEL Institute of Inorganic Chemistry, Slovak Academy of Sciences, SK-842 36 Bratislava, Slovakia INTRODUCTION Infrared (IR) spectroscopy has a long and successful history as an analytical technique and is used extensively (McKelvy et al., 1996; Stuart, 1996). It is mainly a complementary method to X-ray diffraction (XRD) and other methods used to investigate clays and clay minerals. It is an economical, rapid and common technique because a spectrum can be obtained in a few minutes and the instruments are sufficiently inexpensive as to be available in many laboratories. An IR spectrum can serve as a fingerprint for mineral identification, but it can also give unique information about the mineral structure, including the family of minerals to which the specimen belongs and the degree of regularity within the structure, the nature of isomorphic substituents, the distinction of molecular water from constitutional hydroxyl, and the presence of both crystalline and non-crystalline impurities (Farmer, 1979). The interpretation of the absorption spectra of the Source Clays in the middle-IR (MIR) region (4000– 400 cm 1) given here follows those of Farmer and Russell (1964), Farmer (1974a, 1979) and Russell and Fraser (1994). In addition, reflectance spectra in the near-IR (NIR) region (11,000–4000 cm 1), where overtones and combination vibrations occur, are included. These spectra provide information on structural OH groups and H2O in clay...
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...Chapter 1 INTRODUCTION 1.1 Background of the Study A synchronous electric motor is an AC motor distinguished by a rotor spinning with coils passing magnets at the same rate as the power supply frequency and resulting rotating magnetic field which drives it. Another way of saying this is that it does not rely on slip under usual operating conditions and as a result, produces torque at synchronous speed. Synchronous motors can be contrasted with an induction, which must slip in order to produce torque. They operate synchronously with line frequency. As with squirrel-cage induction motors, speed is determined by the number of pairs of poles and the line frequency. Synchronous motors are available in sub-fractional self-excited sizes to high-horsepower direct-current excited industrial sizes. In the fractional horsepower range, most synchronous motors are used where precise constant speed is required. In high-horsepower industrial sizes, the synchronous motor provides two important functions. First, it is a highly efficient means of converting ac energy to work. Second, it can operate at leading or unity power factor and thereby provide power-factor correction. The operation of a synchronous motor is simple to imagine. The armature winding, when excited by a poly-phase (usually 3-phase) supply, creates a rotating magnetic field inside the motor. The field winding, which acts as a permanent magnet, simply locks in with the rotating magnetic field and rotates along with...
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...IMPACT OF STEALTH TECHNOLOGY ON AIR DEFENCE “Stealth refers to a wide range of steps that can be taken to make aircraft harder to detect. There is a payoff and a price.” - Jay H Goldberg [i] CHAPTER I INTRODUCTION 1. The latest trends in military aircraft manufacturing are towards development and incorporation of technology which can provide with means to avoid detection. This enhances its survivability by reducing its radar signature and hence reducing the possibility of being detected by enemy radars. The degree to which this is achieved differs from aircraft to aircraft. Certain aircraft like the B-2 and F-117 have been manufactured with this technology as the basis and are thus referred to as Stealth Aircraft. In other aircraft, stealth is achieved to a lesser degree but it nevertheless helps them in enhancing their survivability against enemy air defence. The day is not far when this technology is likely to find wide spread use in the field of aviation. 2. The dictionary defines stealth as "evasion of notice". Applied to Aerial Warfare, it implies the ability of an aircraft, or platform, to carry out its mission without being detected. Other terms such as "LO" - low observables, or "RO"- reduced observables, have also been used which imply the same thing. The very concept of 'Stealth' conjures up an image of something moving in secretly without being detected. 'Stealth' technology actually is all about the art of making aircraft, missiles and...
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...EMT 212/4 ANALOG ELECTRONIC II Chapter 2 – Op-amp Application Content 1. 2. Op-amp Application Introduction Inverting Amplifier Non-inverting Amplifier Voltage Follower / Buffer Amplifier Summing Amplifier Differencing Amplifier Integrator Differentiator Comparator Summary Frequency Response Op-amp Application Introduction Op-amps are used in many different applications. We will discuss the operation of the fundamental op-amp applications. Keep in mind that the basic operation and characteristics of the op-amps do not change — the only thing that changes is how we use them Inverting Amplifier Circuit consists of an op-amp and three resistors The positive (+) input to the op-amp is grounded through R2 The negative (-) input is connected to the input signal (via R1) and also to the feedback signal from the output (via RF) Inverting Amplifier V V+ Assume that amplifier operates in its linearly amplifying region. For an ideal op-amp, the difference between the input voltages V+ and V to the op-amp is very small, essentially zero; V V 0 V V Inverting Amplifier V V+ Hence; Vin V Vin iin R1 R1 Inverting Amplifier The op-amp input resistance is large, so the current into the +ve and –ve op-amp inputs terminal will be small, essentially zero V Vout iin RF Vin V V Vout RF R1 V 0 Vin Vout ...
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...voltage is 25 V - 0.7 V = 24.3 V. 5. The PIV must be at least 50 V SECTION 2-2 REVIEW 1. How does a full-wave voltage differ from a half-wave voltage? 2. What is the average value of a full-wave rectified voltage with a peak value of 60V? 3. Which type of full-wave rectifier has the greater output voltage for the same input voltage and transformer turns ratio? 4. For a peak output voltage of 45 V, in which type of rectifier would you use diodes with a PIV rating of 50 V? 5. What PIV rating is required for diodes used in the type of rectifier that was not selected in Question 4? ANSWERS:- 1. A full-wave voltage occurs on each half of the input cycle and has a frequency of twice the input frequency. A half-wave voltage occurs once each input cycle and has a frequency equal to the input frequency. 2. The average value of 2(60 V)/∏ = 38.12 V 3. The bridge rectifier has the greater output voltage. 4. The 50 V diodes must be used in the bridge rectifier. 5. In the center-tapped rectifier, diodes with a PIV rating of at least 90 V would be required. SECTION 2-3 REVIEW 1. When a 60 Hz sinusoidal voltage is...
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