Master of Science / Department of Animal Sciences and Industry / Dale A. Blasi / Low-frequency (LF) radio frequency identification (RFID) transponders (n = 1,993) representing both full-duplex and half duplex air interface technologies were evaluated. Transponders representing five manufacturers and seven types were evaluated for read distance (RD), resonance frequency (RF) and voltage response (VR). LF RFID transceivers (n = 24) were also evaluated for performance and variance as tested by read distance. Transponders were sorted into four categories based on RD performance on three transceivers, “Top 25%,” “Middle 50%,” “Bottom 25%,” and “No Read.” These categories were used for evaluation of transponders and transceivers in experiments one and two, respectively. In experiment one, the mean RF of the “Top 25%” transponders were closer to 134.2 kHz (P < 0.05) within a transponder type (TT). TT and mean RD performance category interacted to affect the VR of transponders (P < 0.05); transponders with lower VR tended to have longer RD within a TT. In experiment two, sixty transponders from the “Middle 50%” were used to evaluate transceivers. Transceivers represented five manufacturers and five transceivers per manufacturer; one transceiver was eliminated from testing due to mechanical problems. There was a significant interaction (P < 0.0001) for TT and transceiver manufacturer. This indicated that transceiver performance was greatly dependant on TT being interrogated. TT and transceiver manufacturer interacted to affect RD variance (P < 0.05) demonstrating that transceiver RD will vary depending on TT being interrogated. In the final study, electromagnetic interference (EMI) was evaluated in fourteen livestock auction markets, four feedlots and five cattle abattoirs. The presence of EMI is known to impair the performance of RFID equipment. However, this phenomenon in livestock management settings has not been quantified in the scientific literature. EMI (134.2 + 25 kHz) was observed in all abattoirs. However, the extent and duration of EMI varied depending on individual abattoir. The processing, load and unload areas were evaluated in commercial feedlots. The most EMI was observed in the processing area. Finally, EMI was observed at the sale ring exit at two livestock auction markets. EMI exists in livestock management settings and may negatively impact the performance of LF RFID.

M.Ing. / This study focuses its attention on conducted common mode EMI. Common mode current is the current that flows from an electrical circuit to a zero reference plane and back to the circuit again. It is known that the manner in which the common mode current flows is through stray capacitances that form between the electrical circuit and the zero reference. This study was aimed at developing a method to measure the value of the stray capacitance of a switching circuit. Determining the value of the stray capacitance by taking physical measurements on a circuit board is a challenge for a number of reasons, one of which is that great care should be taken not to add to the stray capacitance by means of the measuring equipment. By measuring the value of the stray capacitance, it will be possible to model the occurrence of Common Mode EMI better and more accurately. This could, in turn, lead to a reduction in EMI. Any body of an arbitrary shape, size and material exhibits a self-capacitance with respect to a zero reference frame. This principle, together with the principle of conservation of charge, also applies to electrical components, or circuits as a whole. The experimental work was performed on a buck DC-DC converter. The circuit was simplified to aid in analysis. By varying the value of an external capacitance and taking basic measurements, it is then possible to uniquely determine the absolute values of the self-capacitances. For every pair of external capacitance values placed in the circuit (of which one can be =0pF), a value for stray capacitance is calculated. Many data points were recorded with many different external capacitors in the circuit, resulting in a variety of stray capacitance values. In order to obtain a single value, a weighted mean of all the values was calculated. The values obtained in this proposed method of measuring the stray capacitance compares well with that obtained using the Finite Element Method. The advantage of the method presented here is that the self-capacitances are determined under the actual operational conditions, no specialised equipment is required and no unique handling of parasitics is needed. The method relies on very simple measurements and no complex data manipulations are required.

Master thesis examines a selected part of electromagnetic compatibility. In this work, there is theoretically discussed how electromagnetic interference appears and how is spread through free space environment. To eliminate ambient interference signals, the measurements have been performed in anechoic chamber where the undesirable interference signals were suppressed. In the thesis, there are also described parameters of EMI receivers and limits of electromagnetic interference. The description of calculations of the antenna height for finding maximum intensity of electric field strength for standard measurement distance has been made. For proposed transformed measurement distance, calculations of intensity electric field with addition of parameters measuring antenna and object under test were performed. Correction curves for conversion intensity electric field have been obtained as the result.

The interlaminar region is a contributing factor to the limited electrical conductivity of carbon fiber/epoxy composites. Consisting of electrically insulating epoxy matrix between conductive layers of carbon fiber, the interlaminar region prevents electrical interaction between the carbon fiber layers and electrical conduction in the through thickness direction.The interlaminar region in thin [0,0] carbon fiber/epoxy composites has been reinforced by carbon nanotubes (CNT) by two methods. First by aligned CNT forests from N12 Technologies and secondly by self-produced Buckypapers, porous CNT films, of different areal densitites. Two batches of laminates modified by aligned CNTs, having different curing conditions, and laminates modified with Buckypapers were manufactured. The laminates were evaluated by their electrical conductivity and electromagnetic interference shielding efficiency (EMI SE). The addition of external pressure to the laminates during curing brought an increase in longitudinal conductivity, a consequence of higher fiber packing. Also, both reinforcement methods increased the longitudinal conductivity through improved electrical interaction between the carbon fiber layers. However, only the Buckypaper reinforcement augmented the transversal conductivity significantly, acting as a highly conductive route in the interlaminar region. Both batches of aligned CNT modified laminates exhibited equal EMI SE, questioning the influence of the conductivity of the laminate on its EMI SE. Also, the increase in EMI SE brought by the aligned CNT forests were negligible compared to the reference. However, the reinforcement by Buckypapers proved successful, reaching -45/-50 dB at 1000 MHz, improving from 30 dB of the unmodified reference at the same frequency.

As technology becomes more prevalent, its application to safety and security in critical systems continues to increase. This leads to an increased dependence on sensors to provide an accurate view of the environment surrounding an application. These sensors can also be exploited by a malicious individual to attack a system and compromise its safety or security. These attacks change the reported value of a sensor so that it doesn't re ect the real situation. The systems in a car can be used as an example of this. Cars can have numerous sensors that measure a variety of things, including the car's distance from an object, if the tires are locking up, or if the gas is low. The use of these sensors makes cars safer and more convenient to use. Using IEMI, an attacker could compromise some of these systems by changing the reported value so that an object appears further away than it actually is or that the tires aren't locking up when they are, possibly causing the car to crash. By doing this, a malicious individual could compromise the safety or security of a car. This work attempts to understand what would be required for a malicious individual to conduct such an attack, thereby allowing for the identification of systems that are vulnerable to such attacks. This understanding would also provide the basis for designing defenses against these attacks, thereby increasing the safety of society at large.

Objective. To study whether an electrosurgery device interferes with the operation of a low-power spread-spectrum wireless network adapter. Methods. Nonrandomized, unblinded trials with controls, conducted in the corridor of our institution's operating suite using two portable computers equipped with RoamAbout omnidirectional 250 mW spread-spectrum 928 MHz wireless network adapters. To simulate high power electrosurgery interference, a 100-watt continuous electrocoagulation arc was maintained five feet from the receiving adapter, while device reported signal to noise values were measured at 150 feet and 400 feet distance between the wireless-networked computers. At 150 feet range, and with continuous 100-watt electrocoagulation arc five feet from one computer, error-corrected local area net throughput was measured by sending and receiving a large file multiple times. Results. The reported signal to noise (N = 50) decreased with electrocoagulation from 36.42 ± 3.47 (control) to 31.85 ± 3.64 (electrocoagulation) (p < 0.001) at 400 feet inter-adapter distance, and from 64.53 ± 1.43 (control) to 60.12 ± 3.77 (electrocoagulation) (p < 0.001) at 150 feet inter-adapter distance. There was no statistically significant change in network throughput (average 93 kbyte/ second) at 150 feet inter-adapter distance, either transmitting or receiving during continuous 100 Watt electrocoagulation arc. Conclusions. The manufacturer indicates "acceptable" performance will be obtained with signal to noise values as low as 20. In view of this, while electrocoagulation affects this spread spectrum network adapter, the effects are small even at 400 feet. At a distance of 150 feet, no discernible effect on network communications was found, suggesting that if other obstructions are minimal, within a wide range on one floor of an operating suite, network communications may be maintained using the technology of this wireless spread spectrum network adapter. The impact of such adapters on cardiac pacemakers should be studied. Wireless spread spectrum network adapters are an attractive technology for mobile computer communications in the operating room.

This thesis develops a novel method to predict radiated emissions measurements. The techniques used are based on standard Electromagnetic Compatibility (EMC) qualification test methods. The empirical data used to formulate the final results was restricted to pertinent data protocol waveforms however the entire method may be applied to any waveforms for which empirical radiated emissions have been measured. The method provides a concise means for predicting worst case radiated emissions profiles based on empirical measured data.

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This dissertation presents the systematic analysis and the critical assessment of the AC side soft-switching inverters in electric vehicle (EV) applications. Although numerous soft-switching inverter techniques were claimed to improve the inverter performance, compared with the conventional hard-switching inverter, there is the lack of comprehensive investigations of analyzing and evaluating the performance of soft-switching inverters. Starting with an efficiency comparison of a variety of the soft-switching inverters using analytical calculation, the dissertation first reveals the effects of the auxiliary circuit's operation and control on the loss reduction. Three types of soft-switching inverters realizing the zero-voltage-transition (ZVT) or zero-current-transition (ZCT) operation are identified to achieve high efficiency operation. Then one hard-switching inverter and the chosen soft-switching inverters are designed and implemented with the 55 kW power rating for the small duty EV application. The experimental evaluations on the dynamometer provide the accurate description of the performance of the soft-switching inverters in terms of the loss reductions, the electromagnetic interference (EMI) noise, the total harmonic distortion (THD) and the control complexity. An analysis of the harmonic distortion caused by short pulses is presented and a space vector modulation scheme is proposed to alleviate the effect. To effectively analyze the soft-switching inverters' performance, a simulation based electrical modeling methodology is developed. Not only it extends the EMI noise analysis to the higher frequency region, but also predicts the stress and the switching losses accurately. Three major modeling tasks are accomplished. First, to address the issues of complicated existing scheme, a new parameter extraction scheme is proposed to establish the physics-based IGBT model. Second, the impedance based measurement method is developed to derive the internal parasitic parameters of the half-bridge modules. Third, the finite element analysis software is used to develop the model for the laminated bus bar including the coupling effects of different phases. Experimental results from the single-leg operation and the three-phase inverter operation verify the effectiveness of the presented systematic electrical modeling approach. With the analytical tools verified by the testing results, the performance analysis is further extended to different power ratings and different bus voltage designs. / Ph. D.