The spread of the 5G technology in the telecom power applications increased the need to supply high power density with higher efficiency and higher power factor. Thus, in this paper, the performance of the different power factor correction ( PFC ) topologies implemented to work with high power density telecom power applications are investigated. Two topologies, namely the conventional and the bridge interleaved continues-current-conduction mode (CCM) PFC boost converters are designed. Selection methodology of the switching elements, the manufacturing of the boost inductors, and the optimal design for the voltage and current control circuits based on the proposed small signal stability modeling are presented. The printed circuit board (PCB) for the two different PFC topologies with a power rating of 2 kW were designed. PSIM simulation and the experiments are used to show the supply current total harmonic distortions (THD), voltage ripples, power efficiency, and the power factor for the different topologies with different loading conditions.

This paper presents an optimal design for the inner current-control loop of the continuous current conduction mode (CCM) power factor correction (PFC) stage, which can be used as the front stage of the two-stage AC/DC telecom power supply. The conventional single-phase CCM-PFC boost converter is implemented with proportional–integral (PI) controllers in both the voltage and current-control loops to regulate the output DC voltage to the specified value and to ensure the input current follows the input voltage, which offers a converter with a high-power factor (PF) and low current total harmonic distortion (THD). However, due to the slow dynamic response of the PI controller at the zero-crossing point of the input supply current, the input current cannot fully follow the input voltage, which leads to high THD. In this paper, we investigate a digitally controlled PFC converter with an optimally designed inner current-control loop using a doubly-fed control loops integral-proportional (IP) controller to reduce the THD and to offer an input current with a unity PF. For the economic design of a digitally controlled PFC converter, two isolated AC and DC voltage sensors are designed for interfacing with the microcontroller unit (MCU). PSIM software as well as experimental prototype was used to test the converter performance using the proposed designed current controllers and isolated voltage sensors. We achieved a high-power-density, digitally controlled, telecom PFC stage with a power factor more than 99% and THD of about 5.50%

This paper presents a complete mathematical design of the main components of the 2 kW, 54V direct current (DC)–DC converter stage, which can be used as the second stage of the two stages of alternating current (AC)–DC telecom power supply. In this paper, a simple inrush current controlling circuit to eliminate the high inrush current, which is generated due to a high input capacitor at the input side of the DC-DC converter, is proposed, designed, and briefly discussed. The proposed circuit is very easy to implement in the lab using a single metal–oxide–semiconductor field-effect transistor (MOSFET) switch and some small passive elements. PSIM simulation has been used to test the power supply performance using the value of the designed components. Furthermore, the experimental setup of the designed power supply with inrush current control is built in the lab to show the practical performance of the designed power supply and to test the reliability of the proposed inrush current mitigation circuit to eliminate the high inrush current at initial power application to the power supply circuit. DC–DC power supply with phase shift zero voltage switching (ZVS) technique is chosen and designed due to its availability to achieve ZVS over the full load range at the primary side of the power supply, which reduces switching losses and offers high conversion efficiency. High power density DC–DC converter stage with smooth current startup operation, full load efficiency over 95%, and better voltage regulation is achieved

This study aims to compare different historical predictive master curve techniques which model the rheological properties of asphalt binders in terms of dynamic shear modulus (G*). The investigated models are the Sigmoidal model, Generalized Logistic Sigmoidal model (GLS), Christensen-Anderson model (CA), and Christensen-Anderson and Marasteanu (CAM) model. These models are applied on virgin and sulfur-extended asphalts (SEA). Two types of recycled plastic waste; recycled high-density polyethylene (RHDPE) and recycled low-density polyethylene (RLDPE) are used to modify both the virgin asphalt and SEA. The investigated models are employed to describe the rheological viscoelastic characteristics of the different investigated binders at different aging conditions under the influence of different frequencies and temperatures based on dynamic mechanical analysis (DMA). The results of this study show that the performance of the investigated models is affected by binder modification and aging conditions. The G* of virgin and sulfur asphalts (either modified or virgin) can be satisfactorily represented by all models investigated in this study under original and aged conditions. The most accurate model is the generalized modified sigmoidal model followed by the Sigmoidal model, the CAM Model, and CA Model, respectively

This research evaluates the rheological properties of virgin asphalt and sulfur extended asphalt (SEA) modified with two types of recycled plastic waste (rPW). The investigated plastic wastes are the recycled low-density polyethylene (rLDPE) and recycled high-density polyethylene (rHDPE). It also assesses the environmental and economic benefits of recycling such materials. A total of 16 modified binder samples are produced by adding rLDPE and rHDPE modifiers to virgin asphalt and SEA in four different concentrations of 2%, 4%, 6%, and 8% by weight of asphalt. The basic and rheological properties of the virgin and modified asphalts are explored by conventional tests, and advanced rheological tests at different aging conditions. Finally, cost-effectiveness and environmental analyses are conducted. The environmental benefit analysis is performed by comparing carbon and non-methyl volatile organic compound (NMVOC) emission from the various recycled polyethylene (rPE) with the manufacturing process of the same quantities of virgin LDPE and HDPE when used to modify asphalt. The effect of incorporating sulfur into virgin asphalt on the environment is also determined. Results show that modification yields a higher binder complex shear modulus (G*) and a lower loss tangent (tan δ) at all traffic speeds meaning improved rut resistance behavior under heavy traffic loading and high temperature conditions. About 29% reduction in material cost occurs when rPE-modified SEA is used instead of virgin asphalt. The environmental and economic analyses show that using SEA modified with rPE for road construction is an economic, sustainable, and ecological alternative with better performance compared to virgin asphalt.

This paper documents the testing of six 20 ft × 4 ft × 8 in. (6.1 m × 1.2 m × 203.2 mm) precast, prestressed concrete sandwich panels constructed with continuous rigid insulation and a carbon-fiber-reinforced polymer grid shear transfer mechanism. All panels were identical except for foam type and were cast together on the same prestressing bed. Three of the six panels were fabricated with expanded polystyrene (EPS) foam insulation, and the remaining three panels were fabricated using sandblasted extruded polystyrene (XPS) foam. For each group of three panels, one was tested to failure as a control and two others were cycled 2 million times to 45% of their design ultimate load before failure testing. The tested EPS panels all failed when the applied lateral load was greater than or equal to 100 lb/ft² (4.79 kPa), which is 2.35 times their design load of 42.5 lb/ft² (2.03 kPa). The tested XPS panels all failed at the equivalent of 175 lb/ft² (8.38 kPa) of applied lateral pressure, which is more than 4.0 times their design load of 42.5 lb/ft². All four panels subjected to fatigue survived 2 million lateral load cycles without any visible signs of degradation.

The design procedure presented in the seventh edition of the PCI Design Handbook: Precast and Prestressed Concrete for ledges of L-shaped beams has been called into question by many engineers and researchers. Research findings from previous experimental studies have indicated that the PCI ledge design equations can overestimate ledge punching shear strength. This paper presents the development of the design procedure for the eighth edition of the PCI Design Handbook to evaluate the punching shear strength of ledges of L-shaped beams. Based on the failure surfaces observed throughout a comprehensive experimental program, an idealized failure surface was determined. The results of extensive finite element analyses and a large experimental program were used to evaluate the effects of global stress on ledge capacity, and a procedure to evaluate the punching shear strength of the ledge was developed. The proposed procedure is presented in this paper and is intended to provide an improved margin of safety for ledge capacity under a wide range of loading conditions. Consideration was given to ensure simplicity and practicality of the proposed design procedure.

The ledge design procedure in the seventh edition of the PCI Design Handbook: Precast and Prestressed Concrete has been called into question by several engineers and researchers since 1985. Specifically, the ledge punching-shear capacities predicted by the PCI procedure overestimate the failure loads observed in several previous laboratory tests and analytical studies. This paper presents the results of the second phase of an extensive experimental program conducted on nine fullscale, long-span, L-shaped beams with ledge heights from 8 to 18 in. (200 to 450 mm). The main objectives of this study were to investigate the effects on ledge capacity of several significant parameters, such as global stress, prestressing, ledge height, and concrete strength. In addition, the study also investigated the efficiency of selected special reinforcement details. The experimental results demonstrated that increasing the global stress significantly reduces ledge capacity, while the use of prestressing increases the capacity. The research also demonstrated that concentrating the ledge reinforcement at the load location can significantly increase the ledge capacity, offering a practical design alternative for carrying heavy loads.