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This article proposes a new method for determining the optimal placement and sizing of voltage balancers (VBs) in bipolar DC distribution systems. In bipolar DC systems, asymmetric structures, such as distributed generation, loads, and line parameters, can cause voltage imbalances with respect to the poles. Such imbalances can be mitigated by using VBs that balance local positive and negative voltages in a decentralized manner, similar to voltage compensators in conventional AC systems. In this study, a deterministic optimization model is formulated to minimize the installation cost of VBs while maintaining the voltage imbalance within the allowable range. The model is proposed with mixed-integer linear programming using the big-M method and current-injection power flow equations. Subsequently, the uncertainty boundaries of renewable energy sources and loads are incorporated to formulate a robust optimization model as a tri-level optimization problem, which is solved using a column and constraint generation framework. The case study validates the effectiveness of the proposed method for mitigating voltage imbalances with minimum investment cost in bipolar DC distribution systems.

A phenomenon called “DQ crosstalk” has been discovered in inductive power transfer (IPT) systems that uses a crossed DQ dipole coil for omnidirectional wireless power transfer. Crosstalk refers to nonlinear magnetic interaction between D and Q coils of a DQ dipole coil, in which the current in one coil is affected by the other coil. The crosstalk is investigated in this article and the reason for it is turned out to be magnetic saturation at the intersection part of a DQ coil. Mutual inductance between D and Q coils, which can be minimized for a well-made crossed DQ coil, is identified to be not the major reason for the crosstalk. As one of the D and Q coils is saturated, the inductance of another coil is reduced through the intersection part. Then, the LC resonant frequency of the D or Q coil and its compensation capacitor increases, which results in higher current that eventually leads to saturation. In this way, saturation of one coil stimulates saturation of another coil, and vice versa. When a crossed DQ coil enters to partial saturation, which is inevitable for maximum power delivery in many practical applications, the IPT system can be eventually collapsed due to positive feedback of saturation. The mechanism of DQ coil saturation considering crosstalk is identified and simulated by a finite element method. An experimental prototype of a DQ coil with a test circuit at 9.4 kHz verified the crosstalk phenomenon by evaluating the distortion of one coil current when the other coil is saturated. Crosstalk effects such as inductance variation, phase mismatch, and core temperature increase on an IPT system at 198 kHz were also verified, and remedies for the crosstalk are suggested.

A mechanical method is presented which helps to recover asphalt mastic from asphalt mixture without any chemical agent. It may be used as a surrogate to the current chemical extraction method when asphalt mastic shall be recovered from the asphalt mixture. The presented approach is based on granulation and sieving techniques. For the purpose of validation, the method is compared to the standard chemical extraction method which uses a chemical agent to recover the asphalt binder from the mineral aggregates. Both methods are compared in terms of recoverable amount of mastic, and of filler/binder ratio, of reproducibility, and of suitability of the recovered mastic sample for subsequent temperature and frequency sweep (T-f sweep) tests using a Dynamic Shear Rheometer (DSR).

The electric vehicles (EVs) charging stations (CSs) at public premises have higher installation and power consumption costs. The potential benefits of public CSs rely on their efficient utilization. However, the conventional charging methods obligate a long waiting time and thereby deteriorate their efficiency with low utilization. This paper suggests a novel fuzzy integer linear programming and a heuristic fuzzy inference approach (FIA) for CSs utilization. The model introduces the underlying fuzzy inference system and a detailed formulation for obtaining the optimal solution. The developed fuzzy inference incorporates the uncertain and independent available power, required state-of-charge, and dwell time from the power grid and EVs domains and correlates them into weighted control variables. The FIA automates the service provision for the EVs with the most urgent requirements by resolving the objective function utilizing the weighted control variables, thereby optimizing the waiting time and the CSs utilization. To evaluate the effectiveness of the proposed FIA, several case studies were conducted, corresponding to different parking capacities and installations of CSs. Moreover, the simulations were conducted on EVs with varying battery capacities, and their performance was evaluated based on several metrics, including average waiting time, utilization of CSs, fairness, and execution time. The simulation results have confirmed that the effectiveness of the proposed FIA scheduling method is considerably higher than that of the other methods discussed.

Asphalt mastic is known to play an important role when determining the fatigue performance of asphalt mixture. Time sweep test using a Dynamic Shear Rheometer can be used. However, a long testing time is a major disadvantage, and no guidelines for testing asphalt mastic are available. Therefore, this study presents an Accelerated Dynamic Shear Rheometer Fatigue Test (ADFT) for fatigue testing of asphalt binders and mastics. Asphalt binder of the types 50/70 and 25/55-55 A, and corresponding asphalt mastics were tested. The results were analysed in regard to consistency of test results, efficiency of testing time, and repeatability. ADFT showed better applicability than conventional time sweep test, and ADFT reduced testing time significantly. Repeatability was improved.

Using reclaimed asphalt material for rehabilitation and construction of new asphalt pavements is currently a common practice not only in view of the economic benefits associated with this process but also because of the reduced exploitation of natural resources. For this reason, road authorities have implemented recommendations and guidelines to regulate the use of reclaimed asphalt pavement (RAP) and other recycled materials such as industrial by-products. Nevertheless, the combined use of different recycled materials is not commonly addressed. In this paper, the effect of adding RAP and taconite (a mining by-product) on fatigue and low temperature properties of asphalt mixture was investigated with two different testing geometries: indirect tensile (IDT) and semi-circular bending (SCB). Fatigue behavior, creep stiffness, relaxation modulus, low temperature fracture energy, and fracture toughness were also evaluated, computed, and then compared. A more brittle behavior was observed for mixture prepared with RAP material, however, the mechanical performance was not significantly different for mixtures containing 20% RAP alone and in combination with 50% taconite compared with conventional asphalt mixtures designed with virgin material. This was not the case when RAP content was increased up to 50%, showing a substantially poorer response both in terms of fatigue and low temperature characteristics and suggesting the RAP had a dominant effect. The present exploratory research seems to support the idea of combining RAP and different industry by-products, such as taconite, as long as the RAP content is kept below a specific threshold.

This study aimed to investigate the impact of implementing a primary care physician (PCP) counseling program for the youth population with healthcare needs. This quasi-experimental study used a nonequivalent control group pretest-posttest design, and was conducted at Salim Health Innovation Clinic in Seoul between February and October 2019 comprising 46 participating youths (intervention group) and 48 nonparticipating youths (control group). After 6 months of implementation, drinking (alcohol use control) decreased significantly in the intervention group (0.84 points). There was a significant difference in the anxiety level with a decrease of 2.86 and 0.65 points in the intervention and control groups (P = .011) respectively. There was also a significant difference in the health responsibility domain (P = .04). Moreover, a significant difference in self-efficacy level was found with a mean increase of 0.18 and 0.16 points in the intervention and control groups (P = .001), respectively. The youth population is more prone to neglect self-care due to poor physical and mental health status and no hope for the future because of a lack of jobs and rising housing prices. The program reinforces health-promoting behavior for managing stress and practicing eating high-quality meals, regular exercise, and regular health screening, which can help implement continuous and effective healthcare.

The thermotropic liquid crystalline polyesters (TLCPs) with two kind of methylene groups in a main chain were synthesized by melt polycondensation. One molecule has repeating units in the following compositionwhere Ph means p-phenylene unit and x was controlled to have values of 1, 0.7, 0.5, 0.3, and 0. The random copolyesters (x=0.7, 0.5, and 0.3) revealed lower melting temperatures and wider nematic ranges between melting and isotropic transition temperatures than the two homopolyesters (x=1 and 0). The blends of poly(ethylene terephthalate) and TLCPs with x=1, 0.7, and 0.3 were prepared by twin screw extrusion. A sheet of the blend was prepared by single screw extrusion and sheet casting, and a film was made by stretching biaxially and annealing the sheet. The effect of TLCP on crystallization rate was dominant in the sheet while TLCP addition itself did not contribute much to the crystallization when compared with the stress induced crystallization in the cold stretching of a stretched and quenched film. The strength and modulus were improved in transverse direction (TD) as well as in machine direction (MD) by adding TLCP. In particular the blend film with random copolyester having x=0.3 showed high improvements in strength and modulus. The dimensional stability of the film was also improved by the addition of the TLCPs.

Pleural effusions are associated with a variety of disease states, rendering the differential diagnosis challenging. Spondylodiscitis is an uncommon disease, and its prompt diagnosis can reduce morbidity and mortality. However, an atypical manifestation of the disease, such as pleural effusion, can result in delayed diagnosis. A 76-year-old woman presented with back pain and right pleural effusion. Magnetic resonance imaging revealed paravertebral soft tissue infiltration, with enhancement of bone marrow and intervertebral disk at the T8 and T9 levels, suggesting spondylodiscitis. In patients with exudative pleural effusion, spondylodiscitis may be the cause, so careful analysis of imaging is necessary.