Miracle-dz/UniFAR-FTUs huggingface dataset:
A 77-GHz antenna in package

A novel 77-GHz directional folded dipole antenna integrated in an embedded wafer level ball grid array (eWLB) package is presented. For the characterization of the antenna a frequency multiplier is embedded, which scales the 4.25-GHz input signal up to 76.5 GHz and allows the use of a commercial signal source. The antenna structure is manufactured at the metallic layer, in the fan-out area of the package, and directly connected to the monolithic integrated frequency multiplier. The gain of the antenna is about 7 dBi, measured over a large bandwidth of about 8 GHz. The combination of the frequency multiplier with the on-package antenna is a promising approach to future radar modules in a single eWLB package for automotive radar applications. Such a module avoids 77-GHz transitions to the PCB and hence simplifies the design and manufacturing of the radar sensor significantly.
The effect of grain improvement on carrier lifetime in perovskite solar devices

The grain size of the organometallic halide perovskite, methylammonium lead iodide (MAPbI3) was modified through a solvent annealing technique. Dimethyl sulfoxide (DMSO) solvent was found to coalesce perovskite grains leading to improved carrier lifetimes and solar device performance. Samples with three ratios (1.0, 1.1, and 1.2) of PbI2/(CH3NH3I) were used for this study. SEM images of the film surface showed improvement in the grain size with the amount of the solvent used during the annealing. In addition, the number of pinholes was also reduced by solvent annealing. The increased grains directly lead to increased carrier lifetimes and the device efficiency. The optimal device efficiency was observed for the ratio 1.1 of PbI2/(CH3NH3I) and the solvent volume of 5 μL As the solvent volume increased further, segregated regions of lead rich grains formed among the large grains, which in turn reduced the device efficiency.
Security-Constrained Unit Commitment With Volatile Wind Power Generation

This paper presents a security-constrained unit commitment (SCUC) algorithm which takes into account the intermittency and volatility of wind power generation. The UC problem is solved in the master problem with the forecasted intermittent wind power generation. Next, possible scenarios are simulated for representing the wind power volatility. The initial dispatch is checked in the subproblem and generation redispatch is considered for satisfying the hourly volatility of wind power in simulated scenarios. If the redispatch fails to mitigate violations, Benders cuts are created and added to the master problem to revise the commitment solution. The iterative process between the commitment problem and the feasibility check subproblem will continue until simulated wind power scenarios can be accommodated by redispatch. Numerical simulations indicate the effectiveness of the proposed SCUC algorithm for managing the security of power system operation by taking into account the intermittency and volatility of wind power generation.
A CMOS Chopper Offset-Stabilized Opamp

In this paper we introduce an offset-stabilized operational amplifier that uses a chopper amplifier in a low frequency path to cancel the offset of a wide-bandwidth amplifier. A sample-and-hold circuit is used to reduce the chopper ripple, and the low frequency path is also offset-stabilized to further reduce the residual offset. The amplifier has 1muV offset at a 4 kHz chopper frequency, and a unity gain frequency of 1.3MHz with a 50pF load. The amplifier was realized in a 0.7mum CMOS process, and has an effective chip area of 3.6mm2
Predicted outdoor energy yield of Si based tandem solar cells

Silicon based tandem solar cells have recently received a lot of attention. They are promising candidates to provide the next efficiency boost at moderate fabrication costs. This potentially enables their application in non-concentrating PV systems. It is known that tandem solar cells are sensitive to outdoor irradiation variations, which are more pronounced for non-concentrating applications. Therefore it is important to assess their yield under realistic operating conditions. In this work we analyze the distribution of outdoor conditions measured in Singapore, and calculate the device efficiency losses for these conditions. We find that 2 terminal tandem devices suffer substantially from current mismatch losses, which can amount to 3% to 5% of the rated efficiency under standard testing conditions (STC). Despite this, the predicted performance ratio for tandem solar cell is still on par or better than conventional single-junction Si solar cells. Adjusting the top cell thickness to match the current of the bottom cell under the average Singapore spectrum can decrease the loss due to current mismatch and increase overall yield by 0.8% to 1.7%.
A Study on the Relationship between Organizational Slack and Technology Innovation

Since 1980s, most research regarding firm competitive advantage strategy focuses on the relationship between organizational factors and firm performance, either using resource-based view or capability-based view. The findings with resource-based view and capability-based view cannot illustrate the essential characteristics of forming and maintaining firm competitive advantages when the environmental changing greatly. The present dissertation proposes an integrated resource & capability-based view, which expounds the basic principles and forming paths to achieve firm competitive advantage under super-competitive environment. In order to expound the rationality and effectiveness of the integrated resource & capability-based view, this dissertation proposes a structural equation model which consists of organizational slack, absorptive capabilities and technology innovation factors, and empirically tests the model with data from a questionnaire. 800 firms in Gangdong, Sandong,Sichuan, Liaoning, Shaanxi, Shanxi, Henan and Shanghai participated in this questionnaire. The study of which leads to such a conclusion: the exploitation of the slack assimilated into firm productive system not only produces certain product innovation which enhances differential competitive advantage, but also produces process innovation to enhance cost advantage for firms.
Spatial coherence and its relationship to human tissue: An analytical description of imaging methods

This paper describes the spatial coherence properties of the signal backscattered by human tissue and measured by an ultrasound transducer. Fourier acoustics are used to describe the propagation of ultrasound through a model of tissue that includes multiple reverberations and random scatterers in the imaging plane. The theoretical development describes the evolution of the spatial coherence as it propagates through the near-field tissue layers, is reflected at the focus, and is received at the transducer surface. Simulations are used to propagate the acoustic field through a histologically measured representation of the human abdomen and to validate the theoretical predictions. In vivo measurements performed with a diagnostic ultrasound scanner demonstrate show that simulations and theory closely match the measured spatial coherence characteristics in the human body. The theoretical framework and simulations are then used to describe the physics of spatial coherence imaging, a type of ultrasound imaging that measures tissue's scattering properties with high resolution and contrast.
Construction of optimal bases for wavelet packet modulation under phase offset errors

Wavelet Packet Modulation (WPM) is a new multi carrier communication technique where orthogonal wavelet packet (WP) bases modulated by information bearing symbols are superimposed and transmitted. The orthogonal WP bases are obtained from fundamental two-channel half-band high and low pass filter pairs. The advantage is that by altering the properties of these filters the transmission characteristics of the WPM system can be customized to a given design specification. In this article we evaluate the impact of phase offset on the WPM system performance analytically and derive WP bases that better tackle phase offset errors. The mathematical expressions for the disturbances in WPM transmission caused by phase errors are derived and the design objective is posed as an optimization problem. Numerical solvers are used to solve the problem and the performances evaluated through simulation studies.
Development of lattice-matched 1.7 eV GalnAsP solar cells grown on GaAs by MOVPE

To advance the state-of-the-art in III-V multijunction solar cells towards high concentration efficiencies approaching 50%, development of a high-quality ∼1.7 eV second junction solar cell is of key interest for integration in five or more junction devices. Quaternary GalnAsP solar cells grown lattice- matched on GaAs allows bandgap tunability in the range from 1.42 to 1.92 eV and offers an attractive Al-free alternative to conventional AlGaAs solar cells. In this work, we investigate the role of growth temperature towards understanding the optimal growth window for realizing high-quality GalnAsP alloys. We demonstrate bandgap tunability from 1.6 to 1.8 eV in GalnAsP alloys for compositions close to the miscibility gap, while still maintaining lattice-matched condition to GaAs. We perform an in-depth investigation to understand the impact of varying base thickness and doping concentration on the carrier collection and performance of these 1.7 eV GalnAsP solar cells. The photo- response of these cells is found to be very sensitive to p-type zinc dopant incorporation in the base layer. We demonstrate prototype 1.7 eV GalnAsP solar cell designs that leverage enhanced depletion width as an effective method to overcome this issue and boost long-wavelength carrier collection. Short-circuit current density (Jsc) measured in field-aided devices were as high as 17.25 m A/cm2. The best GalnAsP solar cell in this study achieved an efficiency of 17.2% with a Jsc of 17 m A/cm2 and a fill-factor of 86.4%. The corresponding open-circuit voltage (Voc) of 1.18 V measured on this cell represents the highest Voc reported for a 1.7 eV GalnAsP solar cell. These initial cell results are encouraging and highlight the potential of Al-free GalnAsP solar cells for integration in the next generation of III-V multijunction solar cells.
An experimental comparison of nonholonomic control methods: Automatic parking benchmark

This paper presents several experimental results for typical nonholonomic control methods. Although numerous nonholonomic control methods have been proposed, few is known about the advantages and disadvantages of each method. So in this paper an automatic parking system is used as a benchmark to test several typical nonholonomic control approaches experimentally. The emphasis is put on the applicability and control performance.
A Novel Calculation Method for Iron Loss Resistance Suitable in Modeling Permanent Magnet Synchronous Motors

This paper proposes a calculation method for iron loss resistance that is suitable for modeling permanent magnet synchronous motors. The proposed method is based on the linear feature between semi-input power and square of speed electromotive force. The iron loss resistance is calculated from the slope of this linear function in the offline manner. The advantage of the proposed method is that the iron loss resistance can be calculated directly without any measurements related to mechanical loss. The proposed method can be executed at any load conditions. The validity of the proposed method is experimentally confirmed by the comparison between the actual torque and the calculated torque containing the iron loss resistance.
Mapping optimization for space-time bit-interleaved coded modulation with iterative decoding

For space-time bit-interleaved coded modulation (ST-BICM) systems with iterative decoding, the overall perfor- mance is affected by the chosen mapping. In bit error rate (BER) curves, one mapping reaches an error floor at a low signal- to-noise ratio (SNR), while other mappings result in a lower error floor at a higher SNR. The constellation mappings are divided into groups where each group exhibits a distinctive BER curve. We show that the convergence abscissa of the system depends on the average total bit errors and the harmonic mean of the minimum squared Euclidean distance. In this paper, we characterize all mapping groups for ST-BICM with 8PSK and present the optimal selection for each mapping group over independent fading channels. I. INTRODUCTION Space-time coding techniques significantly improve trans- mission efficiency in radio channels by using multiple transmit and/or receive antennas and coordination of the signaling over these antennas. Bit-interleaved coded modulation with iterative decoding (BICM-ID) gives good diversity gains and Euclidean distance property with higher order modulation schemes using well known binary convolutional codes (1). Tonello (2) combined these two schemes as space-time BICM (ST-BICM) with Gray mapping. In this paper, we will first show that the asymptotic BER performance of ST-BICM system is equivalent to the single antenna BICM-ID case even when the throughput of ST-BICM is higher. This indicates that the total data rate of ST-BICM can be increased linearly with the number of transmit antennas while maintaining the same error probability as BICM-ID. This demonstrates the superior performance of ST-BICM. Motivated by the fact that the ST-BICM performance can be characterized by BICM-ID with the same code and mapping, we optimize the ST-BICM mappings based on the BICM-ID parameters. While the error floor (EF) bound (1) offers a good match for an error floor region, a heuristic analysis is still needed to study BER curve behaviors of BICM-ID for the water fall region. Thus, we derive design considerations based on both
Simple frequency-based sensing of viscosity and dielectric properties of a liquid using acoustic resonators

The effects of a finite polarizability of a liquid sample onto the series resonance frequency of a piezoelectric resonator are described within the small-load approximation. It is found that the sample¿s electrical capacitance (the ratio of surface potential and surface polarization at the crystal surface) enters the motional branch of the equivalent circuit, thereby shifting the series resonance frequency. This effect is caused by piezoelectric stiffening. Using a conventional quartz crystal with small hole in the front electrode and exposing this crystal to a variety of different liquids, we demonstrate that derived equation describes the experiment reasonably well. Electric and dielectric effects are particularly strong for torsional resonators, which operate at a frequency of around 56 kHz. These are in commercial use for determination of the viscosity of engine oils. We propose a simple method to in situ switch the strength of piezoelectric stiffening. It allows separation of the viscoelastic parameters from the electric polarizability. It could, for instance, be used to differentiate between gasoline and water being accidentally admitted to the lubricant reservoir. The instrument requires a single resonator and is based on the determination of only 2 frequency shifts.
Graphene-based dipole antenna for a UHF RFID tag

This paper describes design and measurements of RFID tag built of a graphene-based dipole antenna and a chip operating in the UHF band in accordance with the EPC Global Class 1 Gen. 2 standard. Several tags have been constructed and tested with a standard RFID reader to reveal that each one is fully operational, but the interrogation range for the graphene-based circuits has been limited in comparison to copper antennae. This can be attributed to increased sheet resistance of a graphene layer. However, it seems that for applications were the read range is not crucial the novel antenna can be an alternative to more expensive circuits printed with silver-based inks.
Realizing reconfigurable stub impedance matching networks using MEMS switches

A novel, low loss, and highly reconfigurable matching network based on microelectromechanical system (MEMS) switches is proposed. MEMS switches are employed in an equivalent n-network to realize switchable short circuit stub terminations. The advantage of the proposed device is the minimal loading by MEMS switches in OFF states which results in delivering highly consistent performance over all configurations. The matching network is capable of matching varying impedances on both input and output terminals. Empirical design procedure and requirements for the proposed network is presented and the simulations and measurements for a prototype design are in close agreement.
General-purpose computation method of a power converter for frequency characteristics — Application to stability analysis of a grid inverter

A grid-connected inverter is getting more attention for photovoltaic power generation and smart grid systems, and it must be designed for stable operation. For stability analysis of the system based on the impedance method, its frequency characteristics are needed to assure its stability. This paper proposes a new simple frequency analysis method for a grid-connected inverter system also with a digital controller. Then this also proposes a new frequency analysis method which considers parameter tolerances. It is a sort of the tolerance analysis based on the Monte Carlo method. The frequency characteristics are computed numerically and efficiently by the modified nodal analysis. The proposed computation method is general for any LTI averaged grid-connected system.
The effect of conductor line to meander line antenna design

In this paper, the meander line antenna have been designed to operate at 2.4-GHz for WLAN application. Two different designs of meander line antenna are investigates, without conductor line and with conductor line. The Microwave Office software is used for simulation design process. The antenna is fabricated on a double-sided FR-4 printed circuit board using an etching technique. Then the design has been tested with the advantest network analyzer. The comparison between simulation and measurement results for the return loss and radiation patterns were presented. A bandwidth of 152 MHz and return loss of -37.7 dB were obtained at frequency 2.4 GHz. The gain is comparable to microstrip yagi antenna.
Conjunctival Lymphoma in a Child

Purpose: To report a rare case of large conjunctival B-cell lymphoma in a child. Methods: A 13-year-old girl was initially diagnosed with a right lower eyelid chalazion. After 3 weeks during which the mass was growing, she was referred for treatment to our department. Because of the unusual appearance of the mass, an excisional biopsy was performed. Results: Pathological findings were consistent with those of a large B-cell lymphoma. CD20 and Ki67 staining were positive, and polymerase chain reaction analysis showed monoclonality of B cells. Conclusions: Although conjunctival lymphoma is a very rare entity in children, it should be included in the differential diagnosis of an eyelid or conjunctival mass.
Production of solar-grade silicon: A comparison study of the reduction of SiF4 with Na, Mg, or Al metals

The process of producing solar-grade silicon by direct reduction of SiF4 with Na metal is well established and demonstrated to pilot-plant scale (50 MTY). The silicon obtained contains most impurities, including boron and phosphorus, at levels below 1 ppm. Such silicon has been used to produce solar cells with efficiencies over 18% using commercial manufacturing lines and processes. Recently, we have experimented using Mg and Al as reducing elements. We have shown that Mg may also be a good candidate, and its use may appreciably reduce material costs and total energy required for the solar-grade silicon production. The reduction with Al, although thermodynamically favored, takes place only at high temperatures with a relatively low rate and extent of reaction. In addition, this reaction is complicated by several chemical vapor transport mechanisms. The conclusion is that Al is not attractive reductant for solar silicon production. A comparison study of thermodynamics, the reaction behaviors, and the purity of silicon will be presented.
Modeling Thermal Fatigue in CPV Cell Assemblies

A finite-element (FEM) model has been created to quantify the thermal fatigue damage of the concentrating photovoltaic (CPV) die attach. Simulations are used to compare the results of empirical thermal fatigue equations that have originally been developed for accelerated chamber cycling. While the empirical equations show promise when extrapolated to the lower temperature cycles characteristic of weather-induced temperature changes in the CPV die attach, it is demonstrated that their damage does not accumulate linearly: The damage that a particular cycle contributes depends on the preceding cycles. Direct comparison of the FEM with empirical methods and calculation of equivalent times for standard accelerated test sequences were made using CPV cell temperature histories.
Parametric and dispersion analysis of a dual-pol cavity-backed slot-fed UWB patch antenna

This work focuses on the design approach for a dual-polarized ultrawideband (UWB) patch antenna targeting the frequency range 3.5 - 4.5 GHz. The architecture described in this paper uses the square ring slot feeding approach to increase its bandwidth. In the first part of the manuscript, a tuning analysis of the antenna properties with respect to its geometrical parameters is provided. The second part describes the antenna dispersion characteristics.
Pt/Pd-Fe 3 O 4 Nanoparticles for Removal of Humic Acids and Cr(VI)

Dumbbell-like Pt/Pd-Fe3O4 nanoparticles (NPs) for the effective and simultaneous removal of Humic Acids and Cr (VI) have been prepared by a one-step synthetic approach. The NPs after a ligand exchange process result suitable to be dispersed in water, electrochemical tests were carried out in a batch electrochemical cell. The NPs show excellent removal efficiency for total Cr. In particular ~ 64% of total Cr was removed in 30 min, while ~ 95 % of total Cr was removed in 9 h. Moreover, the complete removal of Cr (VI) was achieved in 1.5 h. Furthermore, they result able to remove ~ 95% of TOC after 9 h electrolysis, indicating a quite complete mineralization to CO2 of HAs.
DC link current minimization for high power current source motor drives

In this paper, a loss reduction and DC link current minimization strategy for a high power current source inverter (CSI) fed drive is proposed. The proposed strategy consists of an inverter maximum modulation index control scheme and a flux optimization algorithm. Specifically, in the inverter modulation index control, the CSI modulation index is kept at the maximum value while the current source rectifier (CSR) is used to regulate a reduced variable DC link current and therefore to control the motor current magnitude. This control scheme can effectively reduce the dc link current and at the same time improve the line side and motor side harmonics. On the other hand, for the optimized flux control, the relationship between the rotor flux and the dc link current is first thoroughly investigated. Based on this analysis, the DC link current from the maximum inverter modulation index control can be further minimized by optimizing the rotor flux according to system variables such as the motor speed, the applied torque and the motor side capacitor size. With the proposed dc current minimization strategy, the drive current rating, semiconductor device losses and the drivepsilas DC link losses can be reduced. Both simulation and experimental results on a 4.16 kV 600 hp CSI fed drive system are obtained to verify the effectiveness of the proposed strategy.