Power Density Levels Research Articles

A Novel Adhesion Map Correlating Adhesion Properties to the Electrode Design Parameters in Lithium-Ion Battery Electrode

Fabricating the electrodes satisfying the targeted energy density, power density, and loading level is not a simple task to achieve because there are interrelated electrode design parameters such as loading level, density, thickness, composition, etc., affecting on the electrode property. Thus far, the time-consuming repetitive trials have been an only answer to achieve this goal. To determine the optimized binder content and the electrode density have been also a difficult question because there has been few systematic research on adhesion properties for LIB electrodes. For instance, the conventional peel test with adhesive tape (3M Scotch tape) has been widely utilized to compare adhesion properties in electrode as a measuring tool. Our group have introduced the Surface and Interfacial Cutting and Analysis System (SAICAS), which are able to measure the shear stress as well as adhesion strength at the interfaces in the LIB electrodes [1-4]. Here in, we utilized the SAICAS to correlate the adhesion property and the typical electrode design parameters–the loading level and the density–by utilizing a SAICAS technique. First, we measured the adhesion properties of LiCoO2 electrodes, having four different electrode densities (2.0, 2.5, 3.0, and 3.5 g cm-3) and three different loading levels (5, 10, and 15 mg cm-2), at the interface between current collector and electrode coating layer and at the middle of the electrode coating layer. Second, from the obtained data, we draw an empirical equation to predict adhesion strength as a function of electrode density and loading level. Third, we verified our attempt was reasonable by predicting the adhesion strength of the LiCoO2electrode randomly chosen in a random loading level and a random density. Acknowledgements This work was supported by the Human Resource Training Program for Regional Innovation and Creativity through the Ministry of Education and National Research Foundation of Korea (NRF-2014H1C1A1066977).

Thermal-Aware Task Scheduling for Energy Minimization in Heterogeneous Real-Time MPSoC Systems

With the continuous scaling of CMOS devices, the increase in power density and system integration level have not only resulted in huge energy consumption but also led to elevated chip temperature. Thus, energy efficient task scheduling with thermal consideration has become a pressing research issue in computing systems, especially for real-time embedded systems with limited cooling techniques. In this paper, we design a two-stage energy-efficient temperature-aware task scheduling scheme for heterogeneous real-time multiprocessor system-on-chip (MPSoC) systems. In the first stage, we analyze the energy optimality of assigning real-time tasks to multiple processors of an MPSoC system, and design a task assignment heuristic that minimizes the system dynamic energy consumption under the constraint of task deadlines. In the second stage, the optimality of minimizing the peak temperature of a processor is investigated, and a slack distribution heuristic is proposed to improve the temperature profile of each processor under the thermal constraint, thus the temperature-dependent system leakage energy consumption is reduced. Through the extensive efforts made in two stages, the system overall energy consumption is minimized. Experimental results have demonstrated the effectiveness of our scheme.

ESTUDO DA PRODUÇÃO DE ENERGIA EÓLICA A PARTIR DE MEDIÇÕES ANEMOMÉTRICAS DA ESTAÇÃO DE CRAÍBAS/AL E SIMULAÇÕES COM O MODELO WASP

Wind energy is seen as one of the promising generation of electricity, as a source of cheap and renewable, is benefit to reduce the environmental impacts of the dam. Along with the hydroelectric networks, the energy produced by the wind will help to increase power generation capacity in the country. That from speed data and direction municipality Wind Craíbas in the corresponding period 2014 - 2015, estimated the wind potential of the region. The tool used in the treatment of the collected data was the Wasp, making simulations of three different levels of measurement, producing a fictitious wind farm with powerful wind turbine. With the model, WASP helps estimate the probability distribution of Weibull and scale parameters A and K. he predominant wind direction is southeast and the best wind power and intensity density levels took place in 70m and 100m high , with about 201 W / m² and 243 W / m² respectively. But when evalua ted the inclusion of fictitious wind farm, the best use happened at 100m tall with production around 73.039 GWh , which can be attributed this improvement to increased efficiency of the wind turbine used in the simulation.

The Design and Evaluation of an Integrated Wire-Bondless Power Module (IWPM) using Low Temperature Co-fired Ceramic Interposer

Abstract This paper presents the plan and initial feasibility studies for an Integrated Wire Bondless Power Module (IWPM). Contemporary power modules are moving toward unprecedented levels of power density. The ball has been set rolling by a drastic reduction in the size of bare die power devices themselves owing to the advent of wide band gap semiconductors like silicon carbide (SiC) and gallium nitride (GaN). SiC has capabilities of operating at much higher temperatures and faster switching speeds as compared with its silicon counterparts, while being a fraction of their size. However, electronic packaging technology has not kept pace with these developments. High performance packaging technologies do exist in isolation, but there has been limited success in integrating these disparate efforts into a single high performance package of sufficient reliability. This paper lays the foundation for an electronic package which is designed to completely leverage the benefits of SiC semiconductor technology, with a focus on high reliability and fast switching capability.

Theoretical Evaluation of Electromagnetic Emissions from GSM900 Mobile Telephony Base Stations in the West Bank and Gaza Strip-Palestine.

Theoretical assessments of power density in far-field conditions were used to evaluate the levels of environmental electromagnetic frequenciesfrom selected GSM900 macrocell base stations in the West Bank and Gaza Strip. Assessments were based on calculating the power densities using commercially available software (RF-Map from Telstra Research Laboratories-Australia). Calculations were carried out for single base stations with multiantenna systems and also for multiple base stations with multiantenna systems at 1.7 m above the ground level. More than 100 power density levels were calculated at different locations around the investigated base stations. These locations include areas accessible to the general public (schools, parks, residential areas, streets and areas around kindergartens). The maximum calculated electromagnetic emission level resulted from a single site was 0.413 μW cm-2 and found at Hizma town near Jerusalem. Average maximum power density from all single sites was 0.16 μW cm-2. The results of all calculated power density levels in 100 locations distributed over the West Bank and Gaza were nearly normally distributed with a peak value of ~0.01% of the International Commission on Non-Ionizing Radiation Protection's limit recommended for general public. Comparison between calculated and experimentally measured value of maximum power density from a base station showed that calculations overestimate the actual measured power density by ~27%.

From single MFC to cascade configuration: The relationship between size, hydraulic retention time and power density

Achieving useful electrical power production with the MFC technology requires a plurality of units. Therefore, the main objective of much of the MFC research is to increase the power density of each unit. Collectives of MFCs will inherently include units grouped in cascades, whereby the outflow of one is the inflow to the next unit; such an approach allows for better fuel utilisation. However, such a configuration is subject to some important considerations, including: the size of the MFCs; the number of units i.e. the length of the cascade; hydraulic retention time; fuel quality; and optimisation of anode surface and microbial colonisation. In the present study, optimisation of the aforementioned aspects has been investigated in order to establish the most appropriate cascade design. Results demonstrate that an increased flow rate of treated urine achieved equal power density with the same setup when fed with fresh urine at a lower flow rate. The independent investigations of these parameters have led to the design of a cascade that maintains uniformity with regard to the aforementioned parameters, by incorporating units of decreasing size, thus allowing locally shorter hydraulic retention times and therefore leading to increased power density levels.

THE AGE-DEPENDENCE OF PERSONAL EXPOSURE TO ELECTROMAGNETIC FIELDS OF WIRELESS COMMUNICATIONS IN INDOOR ENVIRONMENTS

The ever-growing usage of new information and communication technology devices by different age groups is followed with public concerns of exposure induced biological effects. The aim of this paper is to assess and compare personal exposure levels to electromagnetic fields of wireless communications for different age groups, including children, under the same exposure conditions. Assessment of personal exposure of the following age groups: 08-15, 16-20, 21-35 and 36-60 years old is conducted with sophisticated tri-axial E-field frequency selective personal exposure meters, enabling measurements of electric field strength in 14 pre-defined frequency bands in the range of 80 MHz-6 GHz. Participants are selected to be with similar social conditions and occupation, including children, students and administrative employees. The measurements were conducted in typical residential environments collecting 161 280 measurement samples. The mean value of power density of different wireless technologies is presented for each age-group, including the contribute of specific wireless technology to the total personal exposure. The highest personal exposure values per frequency band for all age groups are in GSM and Wi-Fi 2G. The results show a difference in mean power density levels between different age groups for the same exposure environment. Ultimately, all measured values were far below international safety guidelines and exposure limits.

A high power ZnO thin film piezoelectric generator

A highly efficient and large area piezoelectric ZnO thin film nanogenerator (NG) was fabricated. The ZnO thin film was deposited onto a Si substrate by pulsed laser ablation at a substrate temperature of 500°C. The deposited ZnO film exhibited a preferred c-axis orientation and a high piezoelectric value of 49.7pm/V characterized using Piezoelectric Force Microscopy (PFM). Thin films of ZnO were patterned into rectangular power sources with dimensions of 0.5×0.5cm2 with metallic top and bottom electrodes constructed via conventional semiconductor lithographic patterning processes. The NG units were subjected to periodic bending/unbending motions produced by mechanical impingement at a fixed frequency of 100Hz at a pressure of 0.4kg/cm2. The output electrical voltage, current density, and power density generated by one ZnO NG were recorded. Values of ∼95mV, 35μAcm−2 and 5.1mWcm−2 were recorded. The level of power density is typical to that produced by a PZT NG on a flexible substrate. Higher energy NG sources can be easily created by adding more power units either in parallel or in series. The thin film ZnO NG technique is highly adaptable with current semiconductor processes, and as such, is easily integrated with signal collecting circuits that are compatible with mass production. A typical application would be using the power harvested from irregular human foot motions to either to operate blue LEDs directly or to drive a sensor network node in mille-power level without any external electric source and circuits.

13.56 MHz High Density DC–DC Converter With PCB Inductors

This paper presents the design and implementation of a high density 150–200 V to 28 V, 200–400 W resonant dc–dc converter with embedded inductors. The converter has a switching frequency of 13.56 MHz and uses air-core toroidal inductors fabricated with printed circuit board (PCB) technology. Implementing toroidal inductors with the PCB reduces inductance variation. Hence, the tuning and implementation of the converter are simplified while achieving high levels of performance and power density. By not using magnetic cores, the inductors also maintain stable values over a wide temperature range. Moreover, the paper discusses the tradeoffs between simplicity and performance of implementing a hard-switched gate drive at megahertz switching frequencies. We describe the advantages of resonant power converter topologies in applications requiring high density and high performance in demanding environmental conditions.

Studies on Cell-Phone Radiation Exposure inside a Car and near a Bluetooth Device

Electromagnetic radiation emitted by Cell-phones is a new health hazard, especially when they are used inside closed metal bodies such as cars, elevators etc. The modern wireless devices like Bluetooth further enhance the effect of this radiation. The present studies were taken to get quantitative information about the actual power density levels to which a human brain is exposed inside a vehicle while using a cell-phone and a Bluetooth device, and calculation of its specific absorption rate (SAR). The Cell-phone radiation was measured using a handheld portable power density meter TES 593 and specific absorption rates were estimated for human brain tissue from the measured values. These were compared with the SAR values at which biological system of humans and animals start getting affected. The radiation intensity was observed to have increased by 393% when a cell-phone and Bluetooth are used inside a car as compared to no phone/Bluetooth. The specific absorption rates were calculated to be 514 times higher than the biological limit of 1 mW/Kg at exposure frequency of 1800 MHz. The radiation exposure and absorption values were also compared as a function of distance between phone and Bluetooth. The results indicated total exposure intensity and SAR values considerably higher than a human body can safely absorb.

Influence of Lighting Loads upon Thermal Comfort under CBAD and UFAD Systems

Under-floor air distribution (UFAD) systems are occupied-area-based air conditioning systems that generally offer advantages over ceiling-based air distribution (CBAD) systems in terms of energy efficiency and thermal comfort; accordingly, UFAD systems have become more popular lately. The purpose of this study is to provide reasonable UFAD application conditions by comparing and analyzing the influences of cooling loads when UFAD and CBAD are applied to thermally control indoor environments. A chamber experiment was conducted to allow comparisons of the indoor thermal environment under CBAD and UFAD, with the experimental variables of the thermal load of the occupied area and the supply airflow rate. In conclusion, the lower the supply airflow and the higher the lighting power density, the more the thermal comfort of the indoor environment could be improved by using UFAD instead of CBAD. In the lighting power density range of 0–30 W/m2, correlations were calculated whereby the lighting power density levels could be predicted that would ensure thermal comfort at a desired level.

Parameter optimization for microwave coupled with hot air drying process of hawthorn slices using response-surface methodology

The microwave coupled with hot air (MCHA) drying method was used in this test to dry hawthorn slices The effect of initial microwave power density level (6 W/g to 12 W/g), hot air temperature (55°C to 70°C), and hot air velocity (1 m/s to 3 m/s) on the quality attributes of rehydration ratio (Rf), organic acid (OA) and ascorbic acid (AA) of the dehydrated hawthorn slices was analyzed using a response surface methodology. An orthogonal rotatable central composite with three factors and at five levels was used to develop predictive regression models for the responses. The prediction mathematical model of Rf, OA and AA of the hawthorn slice was determined by analysis of variance. Factor and response variables as well as the prediction mathematical model, the optimal drying process of Rf, OA and AA of the hawthorn slice were determined by using the Design-Expert software. The comprehensive optimal conditions were as follows: initial microwave power density 12 W/g, hot air temperature 55°C and hot air velocity 1.56 m/s. Keywords: parameter optimization, response surface methodology, hot air drying, microwave, hawthorn slice DOI: 10.3965/j.ijabe.20150802.1596

Green-induced infrared absorption in annealed proton-exchanged MgO:LiNbO_3 waveguides

The green-induced infrared absorption (GRIIRA) effect in annealed proton-exchanged (APE) MgO-doped LiNbO3 (MgO:LiNbO3) waveguides was investigated experimentally. By directly measuring the green-light-induced transmittance change in the waveguides, the GRIIRA coefficients of the waveguides were studied at a light power density level of several MW/cm2. GRIIRA effects in APE MgO:LiNbO3 and nondoped MgO:LiNbO3 waveguides were compared. The GRIIRA-induced temperature gradient from the waveguide core to the ambient environment was simulated using the measured results. Potential impacts of such temperature gradients on MgO:LiNbO3-based green lasers have been discussed. Optimization temperature control methods have also been discussed.

A microwave wireless energy harvesting system with a wideband antenna array

This paper is focused on a microwave wireless energy harvesting system using a rectenna (rectifying antenna), which consists of a wideband antenna array, a microwave low-pass filter and a voltage doubling rectifying circuit. The wideband antenna array is formed by two double-sided planar cross dipoles. The rectenna operates in the frequency range 1.6–2.5 GHz. Both simulation and experiment studies have been carried out for the rectenna with the input power density levels ranging from 1 to 100 µW/cm2, which are typical in urban environments. The simulated and measured results of the rectenna are compared and showed good agreement. The results demonstrate that the maximum conversion efficiency of the rectenna is above 32% in the frequency range 1.9–2.3 GHz, and the overall conversion efficiency is greater than 20% when the power density is more than 5 µW/cm2. This new wideband rectenna has great potential for harvesting wireless energy in the GSM/3G/4G and ISM 2.4-GHz bands.

Power performance improvements for high pressure ripple energy harvesting

A hydraulic pressure energy harvester (HPEH) device, which utilizes a housing in order to isolate a piezoelectric stack from the hydraulic fluid via a mechanical interface, generates power by converting the dynamic pressure within the system into electricity. Energy harvester prototypes were designed for generating low-power electricity from pressure ripples. These devices generate low-power electricity from off-resonance dynamic pressure excitation. The power produced per volume of piezoelectric material is analyzed to increase the power density; this is accomplished through evaluating piezoelectric stack characteristics, adding an inductor to the system circuit, and solving for optimal loading in order to achieve maximum power output. The prototype device utilizes a piezoelectric stack with high overall capacitance, which allows for inductance matching without using an active circuit. This work presents an electromechanical model and the experimental results of the HPEH devices using a parallel connection of inductive and resistive loads as the energy harvesting circuit. A non-ideal inductive load case is also considered and successfully modeled by accounting for the parasitic resistance of the inductive load. Various HPEH prototypes are fabricated, modeled, and compared in terms of their normalized power density levels, and milli-Watt level average power generation is demonstrated. The highest power density is reported for the single-crystal HPEH prototype.

Analysis of detection limit to time-resolved coherent anti-Stokes Raman scattering nanoscopy

In the implementation of CARS nanoscopy, signal strength decreases with focal volume size decreasing. A crucial problem that remains to be solved is whether the reduced signal generated in the suppressed focal volume can be detected. Here reported is a theoretical analysis of detection limit (DL) to time-resolved CARS (T-CARS) nanoscopy based on our proposed additional probe-beam-induced phonon depletion (APIPD) method for the low concentration samples. In order to acquire a detailed shot-noise limited signal-to-noise (SNR) and the involved parameters to evaluate DL, the T-CARS process is described with full quantum theory to estimate the extreme power density levels of the pump and Stokes beams determined by saturation behavior of coherent phonons, which are both actually on the order of ∼ 109 W/cm2. When the pump and Stokes intensities reach such values and the total intensity of the excitation beams arrives at a maximum tolerable by most biological samples in a certain suppressed focal volume (40-nm suppressed focal scale in APIPD method), the DL correspondingly varies with exposure time, for example, DL values are 103 and 102 when exposure times are 20 ms and 200 ms respectively.

Observation of spectral composition and polarization of sub-terahertz emission from dense plasma during relativistic electron beam–plasma interaction

The paper presents results of measurements of sub-terahertz electromagnetic emission from magnetized plasma during injection of a powerful relativistic electron beam of microsecond duration in plasma with the density of 3 × 1014 cm−3. It was found that the spectrum of the radiation concentrated in three distinct regions with high level of spectral power density. The first region is located near f1 = 100 GHz; the second one is in the vicinity of 190 GHz, and the third region is in the frequency interval f3 = 280–340 GHz. Polarization vectors of the emission in the first and third regions (f1 and f3) are directed mainly perpendicular to the magnetic field in the plasma. At the same time, the polarization of the radiation in the vicinity of f2 = 190 GHz is parallel to the magnetic field. The most likely mechanism of electromagnetic wave generation in the frequency regions f1 and f2 is the linear conversion of the plasma oscillations into the electromagnetic waves on strong gradients of the plasma density. The third region is situated in the vicinity of second harmonic of electron plasma frequency, and we explain this emission by the coalescence of the upper-hybrid oscillations at high level turbulence in plasma.

An Investigation of Wideband Rectennas for Wireless Energy Harvesting

This paper is focused on a wireless energy harvesting system using a rectifying antenna (rectenna). The proposed device consists of a wideband cross-dipole antenna, a microwave low-pass filter and a doubling rectifying circuit using Shottcky diodes as rectifying elements. Previously, a few of wideband rectennas have been investigated at 1.7 to 2.5 GHz. The originality of this paper is on the new wideband rectenna design which can harvest the ambient radio frequency (RF) power at 1.7 to 2.5 GHz. In this system, a new wideband cross dipole is designed and used to achieve the required bandwidth and duel-polarization. In addition, the voltage doubling rectifying circuit is optimized to achieve the best performance at power density levels < 200 μW/cm2 which are typical in urban environments. The characteristics of the proposed rectenna over the desired frequency range are investigated, and the integrated rectenna is simulated, made and tested for low input power densities from 5 to 200 μW/cm2. The simulation and measurement results of the rectenna are compared and a good agreement is achieved. The results demonstrate that the maximum rectenna conversion efficiency is nearly 57% around 1.7 GHz and over 20% over the wideband of interest for the incident power density of 120 μW/cm2. It is noted that the impedance matching is one of the main factors affecting the rectenna energy conversion efficiency. This new wideband rectenna has great potential to harvest wireless energy in GSM/3G/4G and ISM 2.4 GHz bands.

Magnetic Field Configurations Corresponding to Electric Field Patterns That Evoke Long-Term Potentiation Shift Power Spectra of Light Emissions from Microtubules from Non-Neural Cells

Photon counts were measured every 15 ms for 75 s from microtubule-enriched preparations (and nuclei) from mouse melanoma cells during baseline and after 2 min exposures to 1 μT magnetic fields. The magnetic fields were generated from a circular array of solenoids and presented with accelerating or decelerating rotation velocities. The range of photon radiant flux density was in the order of 10-12 W·m-2. Microtubules preparations that had been exposed for only 2 min to a magnetic field configuration corresponding to the electric field pattern that induced long-term potentiation in neural tissue when applied as electric current displayed peaks of spectral power densities within 7 - 8 Hz, 9.5 Hz, 14 - 15 Hz, and 22 Hz bands. The major peak (9.4 Hz) bandwidth was approximately 0.1 Hz. While microtubule preparations exposed for 2 min to a 7 Hz sine-wave or in the absence of a field emitted an overall similar level of spectral power density, the peaks in power density were not present. Treatment with the LTP patterned fields, compared to the baseline or sine-wave fields primarily altered the frequency band in which the amplitude of the photon field was expressed. These results suggest that the photon emissions from microtubule preparations have the capacity to respond to specifically-patterned or geometric shapes of magnetic fields by altering spectral configurations rather than the absolute numbers of photons.

Efficiency Enhancement of a Cantilever-Based Vibration Energy Harvester

Extracting energy from ambient vibration to power wireless sensor nodes has been an attractive area of research, particularly in the automotive monitoring field. This article reports the design, analysis and testing of a vibration energy harvesting device based on a miniature asymmetric air-spaced cantilever. The developed design offers high power density, and delivers electric power that is sufficient to support most wireless sensor nodes for structural health monitoring (SHM) applications. The optimized design underwent three evolutionary steps, starting from a simple cantilever design, going through an air-spaced cantilever, and ending up with an optimized air-spaced geometry with boosted power density level. Finite Element Analysis (FEA) was used as an initial tool to compare the three geometries' stiffness (K), output open-circuit voltage (Vave), and average normal strain in the piezoelectric transducer (εave) that directly affect its output voltage. Experimental tests were also carried out in order to examine the energy harvesting level in each of the three designs. The experimental results show how to boost the power output level in a thin air-spaced cantilever beam for energy within the same space envelope. The developed thin air-spaced cantilever (8.37 cm3), has a maximum power output of 2.05 mW (H = 29.29 μJ/cycle).