Analysis, Design and Validation of a Vaned Diffuser for Improved Fish Friendliness

The primary cause of mechanical-related fish injury and mortality in turbomachinery is blade strike. Fish contained in the flow may strike with the rotor blades and the fixed diffuser vanes, the latter being a non-negligible factor causing fish damage in pump system. In this study, an experiment-based correlation of fish mutilation ratio acts as critical strike velocity. The relation between strike damage in a vaned diffuser and the theoretical pump head is presented as a function of specific speed. As an example, a vaned diffuser is designed for a single-bladed, mixed-flow impeller with the purpose of improving fish friendliness. This pump can be scaled to operate with a head up to 14 m at peak efficiency, without fish damage in the diffuser. Subsequently, experiments are conducted to show the retained pump performance as well as the great improvement of fish friendliness.

Patches of Dual Functions for Wideband MIMO Array Antenna with Linear or Circular Polarization Characteristics

In this paper, a design of a monopole-based four-element MIMO array antenna is proposed. The design is based on a novel technique that makes a patch be a ground plane of the next patch. Thus, each patch has a dual function. This method is named the sharing technique. Thus, for the first time, two of such antennas can be merged, providing a subminiature structure. The method is introduced step by step. Then, a 2×2 MIMO array with a total area of 49×49 mm 2 is designed, which provides a miniaturized of 57% (from 0.18λ 2 0 to 0.076λ 2 0 @ 1.7GHz). Two linearly-polarized array samples are evaluated. One sample with center-fed patches and another with off-center-fed. Both samples provide a semi-end-fire pattern with a minimum front-to-back (F/B) ratio of 11dB and 360° rotation capability with wide 10-dB S 11 bandwidths over 100%. Moreover, an ultra-wideband circularly polarized array with broadside radiation can be achieved by simultaneous, sequential exciting all ports. The antenna achieves isolation better than 15dB, peak efficiency of 95%, and 5.9dBi gain verified with different measurements.

Electric and Magnetic Design of a Deployable WPT System for Industrial and Defense UAV Applications

The following paper presents a highly efficient wireless power transfer (WPT) system for unmanned aerial vehicle (UAV) applications. The proposed system is designed as a deployable landing pad, where UAVs can be efficiently charged at distances up to 20 cm, while the UAV is landing. The operation frequency is 50 kHz. The current work presents two major contributions that help improve this aspect: a novel RX charging pad geometry and an unconventional design of a low-voltage, high-power DC–AC inverter using discrete MOSFET transistors. Both the pad’s geometry and the inverter are designed specifically for UAV applications. The input DC to output AC system efficiency peaks at approximately 95%. The peak efficiency is obtained at power transfers of 625 W. A major difference between the present design and traditionally used state-of-the-art systems is the low DC supply voltage requirement of just 24 V, compared with typical values that range from 50 up to 300 V at similar output power.

A Two-Stage 110VAC-to-1VDC Power Delivery Architecture Using Hybrid Converters for Data Centers and Telecommunication Systems

<p>Improving power delivery and management plays a key role in minimizing the cost of building and operating future green data centers to meet the fast growth of high-performance computing. Toward this important goal, this paper presents a new complete power delivery architecture to bridge AC grid voltages to core levels for computing loads using only 2 conversion stages with new converter topologies. The first stage converts a commercial AC line voltage of 90V-110V to a 48-60V intermediate bus with power factor correction (PFC). The second stage converts the bus voltage to core voltages of ~1 V with high current density and simple duty cycle control. Individually, the first stage was measured at 96.1% peak efficiency for output currents ranging in 0-4.5 A, while the second stage achieved 90.7% peak efficiency with a load range of 0-220 A at 1 V. Measured peak power densities are 73 W/in3 for the first stage and 2020 W/in3 for the second stage. In combination, the direct conversion from a line AC voltage of ~110 VAC to 1 VDC achieves a peak efficiency of 84.1% while providing output currents up to 160A.</p>

A Two-Stage 110VAC-to-1VDC Power Delivery Architecture Using Hybrid Converters for Data Centers and Telecommunication Systems

<p>Improving power delivery and management plays a key role in minimizing the cost of building and operating future green data centers to meet the fast growth of high-performance computing. Toward this important goal, this paper presents a new complete power delivery architecture to bridge AC grid voltages to core levels for computing loads using only 2 conversion stages with new converter topologies. The first stage converts a commercial AC line voltage of 90V-110V to a 48-60V intermediate bus with power factor correction (PFC). The second stage converts the bus voltage to core voltages of ~1 V with high current density and simple duty cycle control. Individually, the first stage was measured at 96.1% peak efficiency for output currents ranging in 0-4.5 A, while the second stage achieved 90.7% peak efficiency with a load range of 0-220 A at 1 V. Measured peak power densities are 73 W/in3 for the first stage and 2020 W/in3 for the second stage. In combination, the direct conversion from a line AC voltage of ~110 VAC to 1 VDC achieves a peak efficiency of 84.1% while providing output currents up to 160A.</p>

Conceptualization and Analysis of a Next-Generation Ultra-Compact 1.5-kW PCB-Integrated Wide-Input-Voltage-Range 12V-Output Industrial DC/DC Converter Module

The next-generation industrial environment requires power supplies that are compact, efficient, low-cost, and ultra-reliable, even across mains failures, to power mission-critical electrified processes. Hold-up time requirements and the demand for ultra-high power density and minimum production costs, in particular, drive the need for power converters with (i) a wide input voltage range, to reduce the size of the hold-up capacitor, (ii) soft-switching over the full input voltage and load ranges, to achieve low losses that facilitate a compact realization, and (iii) complete PCB-integration for low-cost manufacturing. In this work, we conceptualize, design, model, fabricate, and characterize a 1.5kW, 12 V-output DC/DC converter for industrial power supplies that is required to operate across a wide 300 V–430 V input voltage range. This module utilizes an LLC-based control scheme for complete soft-switching and a snake-core transformer to divide the output current with a balanced flux among multiple secondary windings. Detailed loss models are derived for every component in the converter. The converter achieves close to 96 peak efficiency with a power density of 337 W/3 ( 20.6kW/d3m), excellent matching to the derived loss models, and zero-voltage switching even down to zero load. The loss models are used to identify improvements to further boost efficiency, the most important of which is the minimization of delay times in synchronous rectification, and a subsequent improved 1.5kW hardware module eliminates nearly 25% of converter losses for a peak efficiency of nearly 97% with a power density of 308 W/3 ( 18.8kW/d3m). Two 1.5kW modules are then paralleled to achieve 3 kW output power at 12 V and 345 W/3 ( 21.1kW/d3m) with ideal current sharing between the secondary outputs and no drop in efficiency from a single module, an important characteristic enabled by the novel snake-core transformer.

Study the influences of the radionuclide depth distributions on the FEPE for the measurements of the soil activity using in situ HPGe gamma spectrometry

In this work, the influences of the soil densities and the radionuclide depth distributions(RDD) on the Full Energy Peak Efficiency (FEPE) calculation of the in-situ gamma rayspectrometer using the In Situ Object Counting Systems (ISOCS) software were studied. The data of the RDDs at the sites were investigated by using laboratory HPGe gamma spectrometer. Six different RDDs of 40K, 226Ra and 232Th were found at four studied sites with radionuclide deposition moving from surface to deeper positions. The results show that FEPE values vary strongly for the different RDDs, especially for the low gamma ray energies. Use of the uniform model for calculating FEPEs can result in noticeable errors from 29% to 101% for the realistic RDD of the exponential form (surfaceradionuclide deposition), negative variations from 14% to 30% for the realistic RDD of having a radionuclide deposition at the 30 cm depth, and negligible variations of less than 5 % for the realistic RDD of quasi uniform form in the range of gamma ray energies of interest.