Secondhand Jurisprudence in Need of Legislative Repair: The Application of Strict Liability to Commercial Sellers of Used Goods

This Comment will discuss the inability of tort law to provide an adequate solution to this issue, and why this issue should be taken out of the hands of the courts altogether and regulated by state legislatures. State legislatures have the capability to fashion a solution to this problem that would provide adequate compensation to injured consumers without: (1) adversely affecting the used goods market; (2) forcing injured consumers to deal with the expenses and difficulties of litigation using the negligence doctrine or warranty theory; or (3) unfairly holding secondhand dealers liable for defects they did not cause that may put them out of business. In Part II, this Comment will give a brief overview of the history of strict liability for products. Part III will canvass the various policy considerations of strict liability on which courts rely when faced with this issue. Part IV will explain why any solution based on the policy considerations of strict liability is inadequate. Finally, Part V will propose that a no-fault compensation plan fashioned by a state legislature could offer an effective remedy to the problem. Part VI will conclude with some final remarks on the future of products liability law

Principal Component Neural Networks for Modeling, Prediction, and Optimization of Hot Mix Asphalt Dynamics Modulus

The dynamic modulus of hot mix asphalt (HMA) is a fundamental material property that defines the stress-strain relationship based on viscoelastic principles and is a function of HMA properties, loading rate, and temperature. Because of the large number of efficacious predictors (factors) and their nonlinear interrelationships, developing predictive models for dynamic modulus can be a challenging task. In this research, results obtained from a series of laboratory tests including mixture dynamic modulus, aggregate gradation, dynamic shear rheometer (on asphalt binder), and mixture volumetric are used to create a database. The created database is used to develop a model for estimating the dynamic modulus. First, the highly correlated predictor variables are detected, then Principal Component Analysis (PCA) is used to first reduce the problem dimensionality, then to produce a set of orthogonal pseudo-inputs from which two separate predictive models were developed using linear regression analysis and Artificial Neural Networks (ANN). These models are compared to existing predictive models using both statistical analysis and Receiver Operating Characteristic (ROC) Analysis. Empirically-based predictive models can behave differently outside of the convex hull of their input variables space, and it is very risky to use them outside of their input space, so this is not common practice of design engineers. To prevent extrapolation, an input hyper-space is added as a constraint to the model. To demonstrate an application of the proposed framework, it was used to solve design-based optimization problems, in two of which optimal and inverse design are presented and solved using a mean-variance mapping optimization algorithm. The design parameters satisfy the current design specifications of asphalt pavement and can be used as a first step in solving real-life design problems

Analysis and design of a modular multilevel converter with trapezoidal modulation for medium and high voltage DC-DC transformers

Conventional dual active bridge topologies provide galvanic isolation and soft-switching over a reasonable operating range without dedicated resonant circuits. However, scaling the two-level dual active bridge to higher dc voltage levels is impeded by several challenges among which the high dv/dt stress on the coupling transformer insulation. Gating and thermal characteristics of series switch arrays add to the limitations. To avoid the use of standard bulky modular multilevel bridges, this paper analyzes an alternative modulation technique where staircase approximated trapezoidal voltage waveforms are produced; thus alleviating developed dv/dt stresses. Modular design is realized by the utilization of half-bridge chopper cells. Therefore, the analyzed converter is a modular multi-level converter operated in a new mode with no common-mode dc arm currents as well as reduced capacitor size, hence reduced cell footprint. Suitable switching patterns are developed and various design and operation aspects are studied. Soft switching characteristics will be shown to be comparable to those of the two-level dual active bridge. Experimental results from a scaled test rig validate the presented concept

A single-stage three-phase DC/AC inverter based on Cuk converter for PV application

This paper presents a new three-phase dc-ac inverter based on the basic Cuk converter. The main feature of the proposed topology is the fact that the energy storage elements as inductors and capacitors values can be reduced in order to improve the reliability, reduce the size, and the total cost. Moreover, the bucking-boosting inherent nature of the Cuk converter, depending on the time-varying duty ratios, provides more flexibility for stand-alone and grid connected applications when the required output AC voltage is lower or greater than the DC side voltage. This property is not found in the conventional current source inverter (CSI) when the DC input current is always greater than the ac output one or in the conventional voltage source inverter (VSI) as the output ac voltage is always lower than the dc input one. Averaged large and small signal models are used to study the Cuk nonlinear operation. Basic structure, control design, and MATLAB/SIMULINK results are presented in this paper. The new three-phase DC-AC inverter is very convenient for PV applications where continuous average input currents are required for appropriate Maximum power Point Tracking (MPPT) operations

The Effect of Red Blood Cell Velocity on Oxygenation Measurements using Resonance Raman Spectroscopy

Resonance Raman spectroscopy can be used to estimate the hemoglobin oxygen saturation. Previous studies have demonstrated that exposure of oxygenated red blood cells to laser illumination may result in photo-induced displacement of oxygen from hemoglobin. In this study, an in vitro model was used to evaluate the relationship between this photo-induced effect and the red blood cell velocity. A computer-controlled system was implemented to acquire variables such as red cell velocity, microvessel diameter and hemoglobin oxygen saturation at multiple sites in selected microvascular networks. Using this system, resonance Raman spectroscopy was employed to measure hemoglobin oxygen saturation gradients in arterioles and venules of the rat mesentery in vivo. In several in vitro experimental conditions, there was a significant decrease in photodamage as red cell velocity increased. As blood flowed downstream in arterioles and venules, increased red blood cell velocity was associated with smaller hemoglobin oxygen saturation gradients in vivo

Human Occupancy: A Non-Invasive Solution

Currently, it is difficult to find an available location within a crowded setting. To solve this spatial issue, the team wants to be able to inform people of the density in commonly-occupied areas. To do this, they will need to develop Area Occupancy Device Modules (AODMs) to gather thermal readings. After which, the data will be sent to a central coordinator via mesh network communication. This coordinator will then interpret the data and display its analysis in a graphical user interface (GUI). The system is constrained in that it cannot gather defining characteristics of the people it’s observing. Additionally, the system must be able to reliably communicate in a point-to-multipoint architecture. Currently, the team has interfaced a 4x4 thermal sensor/pyroelectric sensor pair. This data is communicated back to the central coordinator (Raspberry Pi) with the use of a mesh network formed by XBee modules. To reduce data corruption the team has implemented their own communication protocol. The current implementation allows for numerous AODMs to relay information back to the central coordinator reliably. Also implemented is a GUI that can be displayed on a television or monitor. Remaining project goals are to develop a more seamless dispersion of information to the user. This can be done via a phone application and/or an online website. Currently, this system is able to reduce the amount of search time for users, and allows for businesses to spatially optimize their surroundings.https://scholarscompass.vcu.edu/capstone/1114/thumbnail.jp

Controlled transition full-bridge hybrid multilevel converter with chain-links of full-bridge cells

This paper proposes a controlled transition full-bridge (CTFB) hybrid multilevel converter (HMC) for medium and high voltage applications. It employs a full-bridge cell chain-link (FB-CL) between the two legs in each phase to generate multilevel bipolar output voltage. The CTFB-HMC has twice dc voltage utilization or power density of conventional converters due to the bipolar capability of its full-bridge configuration. Hence, for the same power rating and same voltage level number, its total cells per phase are quarter that in modular multilevel converter (MMC), which reduces the hardware installation volume. Also, in the proposed converter, the total device number in the conduction paths is the same as in the half-bridge MMC, leading to low conduction losses. The FB-CL current of the CTFB converter has no dc component, which offers the potential to enhance the transient response. Comparative studies between the CTFB and other multilevel topologies are carried out to clarify its main features. The modulation strategies and parameter sizing of the proposed converter are investigated using a generic case. Simulation and experimental results are used to verify the effectiveness of the proposed approach

Single-stage ac–dc buck–boost converter for medium-voltage high-power applications

This study proposes three topologies based on single-stage three-phase ac-dc buck-boost converters suitable for medium-voltage high-power applications. The first two topologies are based on a dual three-phase buck-boost converter, with a three-winding phase-shifted transformer to achieve sinusoidal input currents, with relatively small ac filters. The limitation of these two topologies is the switching devices are exposed either to a high voltage beyond that tolerable by a single device. The third topology is based on three single-phase buck-boost converters; with their dc output terminals connected in series to generate high voltage. By using this approach, voltage stresses on the switching devices are greatly reduced, and sinusoidal input currents with nearly unity power factor is achieved over the entire operating range when using small ac filters. Analysis, PSCAD/EMTDC simulations and experimentation are used to assess the feasibility of the proposed topologies during normal operation. Major findings of this study are discussed and summarised as a comparison between the three topologies