The corrosion protection service life extension provided by epoxy-coated reinforcement (ECR) was determined by comparing ECR and bare bar from 10 bridge decks built between 1981 and 1995. The objective was to determine the corrosion protection service life time extension provided by ECR field specimens with various degrees of coating adhesion: disbonded, partially disbonded, and wholly bonded coatings. The size and length distributions of cracks in Virginia bridge decks were investigated to assess the frequency and severity of cracks. Correlation of cracks with chloride penetration was used to characterize the influence of cracking on deck deterioration. Cracks influence the rate of chloride penetration, but the frequency and width distributions of cracks indicate that cracks are not likely to shorten the overall service life of most bridge decks in Virginia. Altogether, 141 drilled cores, 102 mm (4 inches) in diameter, were employed in this study. For each of the decks built with ECR, 10 to 12 cores were drilled through a top reinforcing bar adjacent to the previous study core locations. In addition, approximately 3 cores were drilled through a top reinforcing bar at a surface crack location. Laboratory testing involved nondestructive monitoring using advanced electrochemical techniques to periodically assess the corrosion state of the steel bars during cyclic exposure to chloride-rich solution over 22 months of treatment. Time of corrosion initiation and time of cracking (where applicable), as well as chloride content of the concrete before and after treatment, were used in the analysis. Less than 25 percent of all Virginia bridge decks built under specifications in place since 1981 is projected to corrode sufficiently to require rehabilitation within 100 years, regardless of bar type. The corrosion service life extension attributable to ECR in bridge decks was found to be approximately 5 years beyond that of bare steel. / Ph. D.

The thermal performance of the power MOSFET module is subject to change over its lifetime. This is caused by the growth of voids and other defects in the die-attach layer. The goal of this dissertation is to develop measurement techniques and finite element simulations that can measure the changes in thermal performance caused by changes in die-attach voided area. These experimental results and simulations can then be used to create predictions of the thermal performance of a particular power semiconductor module at various stages of die-attach fatigue. In the results and simulations presented, a relationship is developed between thermal impedance and void area coverage. This dissertation starts by presenting an analysis of the thermal and mechanical stresses needed for crack and void growth in the power semiconductor die-attach region. Accelerated life testing is then performed for both commercial and prototype power semiconductor devices to generate the stresses needed to precipitate void growth. Representative groups of lead and lead-free solders are then tested to compare levels of die-attach degradation under accelerated life conditions. Hardware is developed to experimentally measure thermal impedance using temperaturesensitive characteristics of the power MOSFET. The power semiconductor devices that were subjected to accelerated life testing are then measured with this hardware. The results show that die-attach voided area coverage increases thermal impedance. Representative lumped parameter thermal models that use R-C circuits are derived to demonstrate the ability of the thermal impedance analyzer to determine the differences in the die-attach layer. Finite element modeling (FEM) is then used on representative voided devices to support these results, with additional emphasis on peak temperatures caused by hotspots located over the voided areas. Experimental techniques are further applied to measurement of cooling trends that occur due to the existence of voids in the die-attach layer. These measurements are correlated with finite element thermal simulations to develop a relationship between thermal impedance, hotspot temperature, die-attach void size, and total voided area coverage. / Ph. D.

Immune checkpoint blockade antibodies have promising clinical applications but suffer from disadvantages such as severe toxicities and moderate patient-response rates. None of the current delivery strategies, including local administration aiming to avoid systemic toxicities, can sustainably supply drugs over the course of weeks; adjustment of drug dose, either to lower systemic toxicities or to augment therapeutic response, is not possible. Herein, an implantable miniaturized device has been developed using electrode-embedded optical fibers with both local delivery and measurement capabilities over the course of a few weeks. The combination of local immune checkpoint blockade antibodies delivery via this device with photodynamic therapy elicits a sustained anti-tumor immunity in multiple tumor models. Named Implantable Miniature Optical Fiber Device (IMOD), this device uses tumor impedance measurement for timely presentation of treatment outcomes, and allows modifications to the delivered drugs and their concentrations, rendering IMOD as outstandingly valuable for on-demand delivery of potent immunotherapeutics without exacerbating toxicities. Rigorous studies performed using IMOD are presented and discussed in the follow chapters, followed by exploration of proposed work to expand the breadth of functions offered by this implantable biomedical platform. / Doctor of Philosophy / Aside from efficient energy and data transfer, optical fibers today are used in varying fields including optogenetics and neuroscience. However, merging fiber optics with therapeutics against cancer has rarely been reported. We establish a versatile polymer/drug integrated optical fiber for both diagnosis and treatment of cancers, with minimum mechanical invasiveness. Release profiles of polymer/drug nanoparticles loaded onto our fibers, regardless of their hydrophilicity, can be adjusted to accommodate both short-term and long-term delivery specifications. This enhances intratumoral drug accumulation with minimal systemic toxicity, thus overcoming the dosing obstacle. The optical fibers are also ideal to be utilized during photodynamic therapy (PDT), since photosensitizers can be easily incorporated and activated by near-infrared light traveling through the fibers. Hollow channel within the optical fiber allows for repetitive on-demand delivery of immune checkpoint inhibitors to surrounding tumor tissue, thus stimulating and reactivating cytotoxic and helper T cells. The synergistic combination of PDT and immunotherapy can potentially boost the tumor-targeted treatment outcome by numerous folds. Lastly, our optical fibers are adaptable to integrate biosensing functionality. Devices are built upon the optical fibers to monitor treatment outcome along tumor regression. Our data establishes a correlation between tumor impedance and tumor volumes, thus allowing us to track tumor progression and treatment response towards administered treatments.

Without noise, a wireless system would be able to transmit and receive signals over an arbitrary long-distance. However, practical wireless systems are not noise-free, leading to a limited communication range. Thus, the design of low-noise devices (such as antennas, amplifiers, and filters) is essential to increase the communication range. Also, it is well known that the noise performance of a receiving radio is primarily determined by the frontend including the antenna, filter, and a low-noise amplifier. In our first design, we intend to reduce the noise level of the receiving system by integrating a parametric amplifier into the slot antenna. The parametric amplifier utilizes nonlinear and/or time-variant properties of reactive elements (capacitors and/or inductors) to amplify radio frequency signals. Also, the parametric amplifier offers superior noise performance due to its reactive nature. We utilize the parametric amplifier to design a low-noise active matching circuit for electrically small antennas in our second design. Using Chu's limit and the Bode-Fano bound, we show a trade-off between the noise and bandwidth of the electrically small antennas. In particular, to make the small antenna wideband, one needs to introduce a mismatch between the antenna and the amplifier. Due to the mismatch, the effect of the low-noise amplifier becomes even more critical and that is why we choose the parametric amplifier as a natural candidate. As a realized design, a loop antenna is configured as a receiver, and the up-converter parametric amplifier is connected to it leading to a low-noise and wideband active matching circuit. The structure is simulated using a hybrid simulation technique and its noise performance is compared to the transistor counterpart. Our simulation and measurement results show more than 20 times bandwidth improvement at the expense of a 2 dB increase in the noise figure compared to the passive antenna counterpart. / Doctor of Philosophy / Nowadays, there is a high demand for compact and high-speed electronic devices such as cellphones, tablets, laptops, etc. It is therefore essential to design a miniaturized wideband antenna. Unfortunately, a trade-off exists between the bandwidth and gain of small antennas. The trade-off is based on some fundamental limits and extends to all small and passive antennas, regardless of their shape or structure. By using an active component such as an amplifier, the gain-bandwidth trade-off can be improved. However, we show that the active component adds noise to the receiving system leading to a new trade-off between noise and bandwidth in the receiving structures. In other words, utilizing the active component does not solve the problem and just replaces the gain-bandwidth trade-off with the noise-bandwidth trade-off. To improve the noise-bandwidth trade-off, we propose a new receiving structure in which we use the parametric amplifier instead of a commercially available transistor amplifier. The noise performance of the parametric amplifier is extremely better than the transistor amplifier leading to lower noise for the specified bandwidth. In particular, we improved the noise performance of the receiving system by 3 dB leading to doubling the communication distance.

In recent years, the ferroelectric oxides belonging to the family of layered perovskite, e.g., SrBi₂(Ta₁₋_xNb_x)₂O₉ (or SBTN), were identified as promising candidates for nonvolatile memory applications. SrBi₂Ta₂O₉ (or SBT) thin films were found to exhibit no fatigue up to 10¹² switching cycles, very good retention properties and low leakage current densities on Pt electrodes. However, high temperature processing, ie. 750 - 800°C, is needed for SBT to exhibit ferroelectric properties. Moreover, the fundamental properties of SBTN have not been fully characterized. In this research, SBTN solid solutions were studied from two aspects: the technical aspect and scientific aspect. From the technical point of view, low temperature processing of SBTN ferroelectric thin films was developed. In this part of study, SBTN thin films were made by metalorganic decomposition method (MOD) and were deposited on Pt-electrodes. The structure development study by a non-destructive optical method, spectroscopic ellipsometry, was proposed to determine nucleation and grain growth temperatures. The information on structure development can be obtained by observing how the refractive indices and film thicknesses change as functions of annealing temperature. The results of structure development study for SBT thin films suggest that the ferroelectric properties are controlled by grain growth process rather than nucleation process. The critical factor for ferroelectric properties was to have grain size exceeding a critical value, i.e., 0.1 µm. Applying this concept, low temperature processing can be achieved by growing larger grains at lower temperature. The processing temperature of SBTN thin films was reduced by 50 - 100°C by adding excess Bi or increasing Nb/Ta ratio. The optimum excess Bi content in SBT was 30 - 50%; within this range, limited solid solution of Bi₂O₃ and SBT was formed. From the scientific aspect of view, optical properties and ionic transport phenomena of SBTN bulk ceramics were investigated for the first time. The reason of using bulk ceramics is to exclude the difficulties associated with thin film technology, e.g., grain size effect and electrode-ferroelectric interface effect. These bulk property studies provide fundamental understanding of SBTN materials and provide a guideline for process development in device applications. The optical dispersion functions of bulk SBTN were obtained by using various angle spectroscopic ellipsometry with a surface layer correction. The values of refractive indices were found to vary with composition, which are possibly associated with crystallographic orientation. Using the Lorentz Oscillator model, the approximate energy band gaps of SBTN solid solutions were estimated to be about 5 eV. The ionic transport phenomena of SBT and SrBi₂Nb₂O₉ (or SBN) were investigated by using impedance spectroscopy. This technique allows to separate the effect of ion transport in grain, grain boundary and electrode-ferroelectric interface. In this study, the fatigue model of bismuth layered oxides was discussed through ionic conductivity and interface absorption effect. One conducting species, oxygen vacancies with positive charges, was assumed in the model. High ionic conductivities of SBT and SBN (~ 10¯⁷ S/cm) comparing to Pb(Zr₁₋_xTi_x)O₃ (~ 10¯¹¹-10¯¹⁰ S/cm) suggests high defect concentration and high charge mobility in bismuth layered oxide materials. As a result, the most possible model to explain high resistance to fatigue of SBT/SBN was the easy recovery of oxygen vacancies from the entrapment at electrode-ferroelectric interfaces. / Ph. D.

Corrosion begins as moisture penetrates the protective barrier of a surface, starting an electrochemical process which over time leads to surface pitting. The combined action of mechanical stresses and corrosion induced pitting reduces structural integrity as the pits enlarge to form nucleation sites for surface cracks, which propagate into through-thickness cracks. In most cases, the total mass loss due to corrosion within the structure is small; however, significant reductions in mechanical strength and fatigue life can occur in the corroded material leading to advanced crack growth rates or fast fracture. Since the structural damage due to localized corrosion pitting is small and the crack growth rates may be large, traditional inspections methods and "find it and fix it" maintenance approaches may lead to catastrophic mechanical failures. Therefore, precise structural health monitoring of pre-crack surface corrosion is paramount to understanding and predicting the effect corrosion has on the fatigue life and integrity of a structure. In this first third of this study, the impedance method was experimentally tested to detect and the onset and growth of the earliest stages of pre-crack surface corrosion in beam and plate like structures. Experimental results indicate the impedance method is an effective detection tool for corrosion induced structural damage in plates and beams. For corrosion surface coverages less than 1.5% and pit depths of less than 25 microns (light corrosion), the impedance method could successfully detect corrosion on plates and beams at distances up to 150 cm from the sensor location. Since the impedance method is a proven tool for corrosion detection, it makes sense to determine how well the method can quantify and track key corrosion variables like location, pit depth, and surface coverage. In order to make fatigue life adjustments for corroded structures it is necessary to quantify those variables. Thus, the second portion of this study uses the impedance method to quantify corrosion location, pit depth, and location. Three separate tests are conducted on beam-like structures to determine how well the damage metrics from the impedance method correlate to the key corrosion variables. From the three tests, it is found that the impedance method correlates best with the changes in corrosion pit depth, so if combined with data from routine maintenance it would be possible to use the impedance method data in a predictive or tracking manner. The impedance method can be correlated to location and surface coverage changes, but the relationship is not as strong. Other NDE techniques like Lamb Waves could use the same sensors to quantify corrosion location, and perhaps surface coverage. The impedance method can detect and quantify pre-crack surface corrosion which leads to shortened fatigue life in structures; however, the sensors must be robust enough to withstand corrosive environments. The last portion of this study tests the following: corrosive effect on Lead Zirconate Titnate (PZT) and Macro Fiber Composites (MFC) sensors, Kapton protected MFC actuators for corrosion detection, and determines if corrosion damage can be sensed on the side of the structure opposite the damage. Sensor recommendations regarding the use of piezoelectric sensors in corrosive environments are made. / Master of Science

With lower output voltage (lower than 1V) and higher output current (more than 160A) required in the near future, the voltage regulators for the microprocessors, a kind of special power supplies are facing more and more critical challenges to achieve high efficiency and high power density. 90% plus efficiency for CPU VRs is expected from industry not only for the thermal management, but also for saving on electricity costs, especially for the large data-center systems. At the same time, high power density VRs are also desired due to the increasing power consumption of microprocessors as well as the precious space on CPU motherboard. Current multi-phase Buck VR has its limitation to achieve 90% plus efficiency. With the state of art devices, the single-stage 12V/1.2V 600kHz Buck VR achieves 85% to 86% efficiency at full load condition. In addition, for the future lower output voltage application, the Buck efficiency will drop another 3~4% due to the extreme small duty cycle. From the power density point of view, due to the switching frequency limitation (normally, from 300 kHz to 600 kHz for typical CPU VRs) for acceptable efficiency performance, the multi-phase Buck VR is unable to ensure a small size since it needs bulky output capacitors to meet the challenging transient requirement as well as the output impedance requirement with relatively low bandwidth design. To attain high efficiency and high power density at the same time, in-series two-stage power architecture was proposed. By cutting the single stage into two and utilizing the low voltage devices, the in-series two stages can achieve around 87% efficiency which is similar as single stage with second-stage operating at 1 MHz for less cost. Compared with the in-series one, the other two-stage power architecture is called "Sigma" architecture which is composed by an unregulated converter (DCX) and a regulated buck converter, with a special connection where the inputs are in series while outputs are paralleled. Through this topology, unlike the in-series two-stage where both two stages deliver the full load power, the power will be distributed between unregulated DCX and regulated Buck. If the unregulated DCX can achieve high efficiency, let most power be handled by it and just small power from buck, the Sigma architecture can achieve high efficiency performance based on this concept. The design consideration and process had been investigated by CPES previous graduates. By the designed 1.2V/120A Sigma VR circuit, approaching 90% efficiency was achieved which is around 3~4% efficiency higher than state of the art multi-phase Buck VR. However, it is not the optimal design for best efficiency performance, the improvement methods for higher efficiency is deeply considered and the efficiency potential benefit of this special structure will be clarified in this thesis. Besides the efficiency interest, transient performance of Sigma VR is also a challenging issue needed to be addressed. The state of the art Buck VR needs a bunch of output bulk capacitors to meet the stringent output impedance requirement from Intel and those output bulk capacitors occupy too much space in the motherboard. For Sigma architecture, through the help of the low impedance DCX which can achieve faster current dynamic response, some low voltage bulk capacitors could be replaced by smaller input high voltage capacitors. It is still not clear for us to identify how input capacitor impacts the DCX dynamic current response and how to best choose this impact factor. This thesis will investigate the faster DCX dynamic current performance of Sigma VR, and explain the dynamic impacts from input capacitors, from control design and from DCX impedance Lout. The high voltage capacitors could provide energy through low impedance DCX to deal with the transient load with smaller capacitance, resulting less total cost and footprint with conventional Buck solution. Low impedance DCX is also a desire for achieving fast current response for providing a "non-obstacle" path when energy transferring from input capacitors. The control also has the impact to the DCX current response when the bandwidth is higher than certain frequency. The transient benefit will also be discussed from impedance perspective. In order to improve the efficiency and power density of Sigma VR, several methods are proposed. As a critical component of DCX, the transformer design determines the performance of Sigma VR both to efficiency and power density. By optimizing the transformer design to achieve lower winding loss and smaller leakage inductance, the higher efficiency and faster transient DCX can be obtained. Changing the output capacitors to ceramic ones is helpful when control bandwidth is greater than 100 kHz for both lower cost and smaller footprint. Continually pushing bandwidth can reduce the required output ceramic capacitor number further. In addition, from the study of the loss breakdown, by adjusting the energy ratio of DCX and Buck can achieve higher efficiency based on current device level. What is more, with the same simple concept of adjusting power ratio of DCX and Buck, with the development of devices in the future as well as higher efficiency DCX, Sigma architecture will be more attractive for future's lower output voltage VR application. And it will also be more efficient considering higher than 12V input bus voltage by letting high efficiency DCX handle more power. Utilizing this characteristic, changing the power system delivery architecture from AC input to the microprocessors, the end to end efficiency could be improved. / Master of Science

The reliable measurement of growth and condition is vital for effective fisheries assessments. Biologists have long attempted to estimate condition for their assessments, but a reliable method to nonlethally estimate body composition is lacking. Proximate analysis is the most dependable and accurate method for estimating internal composition, but it is lethal, time consuming, and expensive. Recent research has shown bioelectrical impedance analysis (BIA) to be an effective method for estimating proximate composition in some fishes. The technique is quick, inexpensive, and, most importantly, nonlethal, which is vital when examining endangered species or cultured fish. My research focused on developing BIA indices for several new species of fish, using those indices to evaluate the body composition of fish in the field, and determining whether water temperature influenced resistance and reactance measurements. I found that BIA accurately estimated the body composition of bluegill Lepomis macrochirus, redear sunfish Lepomis microlophus, brook trout Salvelinus fontinalis, and northern logperch Percina caprodes (r2 ≥ 0.71, p < 0.0001). I also determined that bluegill and redear regressions were not significantly different (P ≥ 0.10) suggesting they can be used interchangeably during future studies. Laboratory studies revealed that water temperature did not significantly influence resistance and reactance measurements of bluegill, redear, and largemouth bass Micropterus salmoides (P ≥ 0.18). These results, along with previous literature, indicate that BIA may be an accurate and reliable assessment tool for fisheries biologists. / Master of Science

Impedance-based Non-Destructive Evaluation for Additive Manufacturing (INDEAM) is rooted in the field of Structural Health Monitoring (SHM). INDEAM generalizes the structure-to-itself comparisons characteristic of the SHM process through introduction of inter-part comparisons: instead of comparing a structure to itself over time, potentially-damaged structures are compared to known-healthy reference structures. The purpose of INDEAM is to provide an alternative to conventional nondestructive evaluation (NDE) techniques for additively manufactured (AM) parts. In essence, the geometrical complexity characteristic of AM processes combined with a phase-change of the feedstock during fabrication complicate the application of conventional NDE techniques by limiting direct access for measurement probes to surfaces and permitting the introduction of internal defects that are not present in the feedstock, respectively. NDE approaches that are capable of surmounting these challenges are typically highly expensive. In the first portion of this work, the procedure for impedance-based NDE is examined in the context of INDEAM. In consideration of the additional variability inherent in inter-part comparisons - as opposed to part-to-itself comparisons - the metrics used to quantify damage or change to a structure are evaluated. Novel methods of assessing damage through impedance-based evaluation are proposed and compared to existing techniques. In the second portion of this work, the INDEAM process is applied to a wide variety of test objects. This portion considers how the sensitivity of the INDEAM process is affected by defect type, defect size, defect location, part material, and excitation frequency. Additionally, a procedure for studying the variance introduced during the process of instrumenting a structure is presented and demonstrated. / Doctor of Philosophy / Impedance-based Non-Destructive Evaluation for Additive Manufacturing (INDEAM) is a quality control approach for detecting defects in structures. As indicated by the name, impedance-based evaluation is discussed in this work in the context of qualifying additively manufactured (3D printed) structures. INDEAM fills a niche in the wider world of nondestructive evaluation techniques by providing a less expensive means to qualify structures with complex geometry. Complex geometry complicates inspection by preventing direct, physical access to all the surfaces of a part. Inspection approaches for parts with complex geometry suffuse a structure with energy and measure how the energy propagates through the structure. A prominent technique in this space is CT scanning, which measures how a structure attentuates x-rays passing through it. INDEAM uses piezoelectric materials to both vibrate a structure and measure its response, not unlike listening for the dull tone of a cracked bell. By applying voltage across a piezoelectric patch glued to a structure, the piezoelectric deforms itself and the bonded structure. By monitoring the electrical current needed to produce that voltage, the ratio of applied voltage to current draw---impedance---can be calculated, which can be thought of as a measure of how a system stores and dissipates energy. When the applied voltage oscillates near a resonant frequency of a structure (the pitch of a rung bell, for example) the structure vibrates much more intensely, and that additional movement dissipates more energy due to viscosity, friction, and transmitting sound into the air. This phenomenon is reflected in the measured impedance, so by calculating the impedance value over a large range of frequencies, it is possible to identify many resonances of the structure. So, the impedance value is tied to the vibrational properties of the structure, and the vibration of the structure is tied to its geometry and material properties. One application of this relationship is called impedance-based structural health monitoring: taking measurements of a structure when it is first built as a reference, then measuring it again later to watch for changes that indicate emerging damage. In this work, the reference measurement is established by measuring a group of control structures that are known to be free of defects. Then, every time a new part is fabricated, its impedance measurements will be compared to the reference. If it matches closely enough, it is assumed good. In both cases, impedance values don't indicate what the change is, just that there was a change. A large portion of this work is devoted to determining the types and sizes of defects that can be reliably detected through INDEAM, what effect the part material plays, and how and where the piezoelectric should be mounted to the part. The remainder of this work discusses new methods for conducting impedance-based evaluation. In particular, overcoming the extra uncertainty introduced by moving from part-to-itself structural health monitoring comparisons to the part-to-part quality control comparisons discussed in this work. A new method for mathematically comparing impedance values is introduced which involves extracting the resonant properties of the structure rather than using statistical tools on the raw impedance values. Additionally, a new method for assessing the influence of piezoelectric mounting conditions on the measured impedance values is demonstrated.

State-of-Health (SoH), a specified measure of stability, is a critical parameter for determining the safe operating area of a battery cell and battery packs to avoid abuse and prevent failure and accidents. A series of experiments were performed to evaluate the performance of a 4P1S battery array using electrochemical impedance spectroscopy to identify key frequencies that may describe battery state of health at any state of charge. Using a large sample number of cells, the state of health frequency, fSoH, for these LiFePO4 26650 cells is found to be 158 Hz. Four experiments were performed to evaluate the lifetime in different configurations: single-cell at 1C (2.6A), single-cell at 10C (26A), four cells in parallel at 10C (ideal match), and four cells in parallel (manufacturer match). The lifetime for each experiment set degraded substantially, with the final parallel series reaching end of life at 400 cycles, a 75.32% reduction in life compared to operating solo. Analysis of the fSoH data for these cells revealed a change in imaginary impedance at the critical frequency that corresponded to changes in the capacity and current data, supporting the development of a single-frequency diagnostic tool. An electrochemical model of the battery was generated, and it indicated the anode material was aging faster than the SEI layer, the opposite of normal cell degradation. A post-mortem analysis of cells from three configurations (baseline, single-cell, and parallel-cell) supported the modeling, as physical damage to the copper current collector in the anode was visible in the parallel-connected cell. / Ph. D. / Lithium-ion batteries are used in a large number of applications, from cellular phones to laptops and electric vehicles. In low power devices, such as a laptop, these batteries can be relatively stable if the associated circuitry is designed properly. However, as the amount of power required from the battery increases, the possibility of an internal battery fault will also increase. The ability to determine the stability of the battery for military applications such as laser weapon systems, electromagnetic railguns or commercial systems such as electric vehicles or industrial-scale micro-grids becomes critical to prevent catastrophic events such as fires. Additionally, the ability to determine the battery State-of-Health (SoH), a specified measure of stability, will enable advance warning of a failing battery to optimize the logistics chain in an operational system. A battery marked as “bad” can be scheduled for replacement before a failure actually occurs. This dissertation has designed a series of experiments that establishes the technology to detect these internals faults, and applies them to a scaled battery system that represents a much larger system. When batteries are placed in parallel and discharged at very high currents, typical of the military applications, the lifetime for the cells was reduced by 75% when compared to batteries discharged under the same conditions by themselves. A post-mortem analysis of cells from three different conditions (uncycled, single-cell, parallel-cell) reveals physical damage to the internal electrodes that indicates a high level of internal destruction occurs at high currents when in parallel arrays.