Hemt’s capability for millimeter wave applications

This paper presents a tutorial review on the High Electron Mobility Transistors (HEMTs)for low-noise and power applications at millimeter wave range frequencies. The major parameters to achieve high performance with such devices are discussed. Present status on power and noise performances is given for InAlAs/InGaAs HEMTs on InP and GaAs substrates.     

Radially inhomogeneous spherical structures; analysis of EM scattering using Taylor’s series method and their potential applications

Spherical structures have always been among the most frequently studied topics by researchers in engineering electromagnetics. In this paper, electromagnetic (EM) scattering from radially inhomogeneous spherical structures is investigated in the most general cases. Unlike previous investigations, these structures are studied based on an exact frequency domain method without any approximations. Two main categories of applicable inhomogeneous spherical structures exist: inhomogeneous spheres and spherical arbitrary cores, coated with a radially inhomogeneous layer. One of the biggest advantages of this research investigation is the generality and inclusiveness in analyzing all of the aforementioned circumstances. The validity of the proposed method is verified for some special types of inhomogeneous structures through comprehensive examples. In the last section, the proposed method is used for designing of the optimized new class of lens based on the physical concept of gradient refractive index material, and radar cross section reduction based on gradual wave absorption. The proposed approach can be used for other interesting applications such as designing radar absorbers, cloaks and radomes for spherical structures in future researches.     

A new method for the fast determination of the data retention lifetime of UV EPROM’s

The newly developped method involves a controlled partial erasure of a charged ultraviolet erasable programmable read only memory device followed by a period of high temperature storage. The model is based on two assumptions: the amount of charge stored at the floating gate of a programmed cell is assumed to be equal throughout a component and the trip the minimum level of charge stored at the floating gate of a programmed cell, has a Gaussian distribution throughout a component. The experimental data are well described by the model. After implementation of the experimental results in the model we extrapolate the data retention lifetimes of the UVEPROM’S under operational conditions. Our measurements show that most of the tested UVEPROM devices (64 ko to 256 ko) have a similar operational lifetime, only the charge leakage activation energy differs (0.35 to 0.9 eV) depending on the type of component. In conclusion this method and model are suitable for a fast determination of UVEPROM’S data retention lifetimes under operational conditions.     

Design method of Chua’s circuit for specified spectrum distribution

Based on the α-β bifurcation curves and the special characteristics of chaotic spectrum of chua’s circuit, this paper presents here a method for designing a Chua’s circuit which approximately satisfy specified spectrum distribution range. Supported by the Nature Science Foundation of Zhejiang Province     

An all digital PLL with an active inductor DCO for LTE applications in 0.13 μm CMOS

In this paper, we propose a low-power all digital phase-locked loop with a wide input range, and a high resolution TDC that uses phase-interpolator and a time amplifier. The resolution of the proposed TDC is improved by using a phase-interpolator which divides the inverter delay time and the time amplifier which extends the time difference between the reference frequency and the DCO clock. The phase noise of the proposed ADPLL is improved by using a fine resolution DCO with an active inductor. In order to control the frequency of the DCO, the transconductance of the active inductor is tuned digitally. To cover the wide tuning range and to operate at a low-power, a three-step coarse tuning scheme is used. In addition, the DCO gain needs to be calibrated digitally in order to compensate for gain variations. The die area of the ADPLL is 0.8 mm² using 0.13 μm CMOS technology. The frequency resolution of the TDC is 1 ps. The DCO tuning range is 58% at 2.4 GHz and the effective DCO frequency resolution is 0.14 kHz. The phase noise of the ADPLL output at 2.4 GHz is −120.5 dBc/Hz with a 1 MHz offset. The total power consumption of the ADPLL is 12 mW from a 1.2 V supply voltage.     

Propagation of short radio waves and the potential of the Earth’s ionosphere radio-sounding method for calculation of maximum usable frequencies

The influence of the ionosphere on propagation of short radio waves is considered. Data on the monthly average diurnal values of critical frequencies at midlatitudes are presented. The applicability of the radio-sounding method to investigation of the state of the Earth’s ionosphere is demonstrated. Comparison of the data obtained from the path sounding of the ionosphere and from the radio-sounding method is performed. It is shown that satellite navigation systems can be used for prediction of the propagation conditions of short radio waves.     

Identifying relevant segments of AI applications adopters – Expanding the UTAUT2’s variables

Artificial intelligence (AI) is a future-defining technology, and AI applications are becoming mainstream in the developed world. Many consumers are adopting and using AI-based apps, devices, and services in their everyday lives. However, research examining consumer behavior in using AI apps is scant. We examine critical factors in AI app adoption by extending and validating a well-established unified theory of adoption and use of technology, UTAUT2. We also explore the possibility of unobserved heterogeneity in consumers’ behavior, including potentially relevant segments of AI app adopters. To augment the knowledge of end users’ engagement and relevant segments, we have added two new antecedent variables into UTAUT2: technology fear and consumer trust. Prediction-orientated segmentation was used on 740 valid responses collected using a pre-tested survey instrument. The results show five segments with different behaviors that were influenced by the variables of the proposed model. Once known, the profiles were used to propose apps to AI developers to improve consumer engagement. The moderating effects of the added variables—technology fear and consumer trust—are also shown. Finally, we discuss the theoretical and managerial implications of our findings and propose priorities for future research.     

Thermal transient characterization of semiconductor devices with multiple heat sources—Fundamentals for a new thermal standard

The thermal performance of semiconductor devices is most often specified according to JEDEC standards JESD51 1-14 which describes precisely how various steady-state thermal metrics are to be measured. Most of these metrics represent a thermal resistance between the junction of a semiconductor and some reference; e.g. R_th-JA (Junction-to-ambient), R_th-JB (Junction-to-board), or R_th-JC (Junction-to-case). However all of the above thermal metrics characterize the steady-state behavior and have been designed for semiconductors with a single heat source only. While the extension of a stationary thermal resistance R_th-JX to the corresponding transient thermal impedance Z_th-JX is straightforward the adaptation of existing standards for the characterization of devices with multiple heat sources is far less obvious. This publication gives an overview on the theoretical framework which allows extending the existing thermal metrics in a compliant way. We demonstrate the method utilized for thermal impedance matrix measurements and show how thermal surroundings affect the thermal relations inside the package.     

Diffraction of a plane electromagnetic wave by a circular dielectric cylinder with a finite-length perfectly conducting metal strip on the Cylinder’s lateral surface

The diffraction of E-and H-polarized plane electromagnetic waves by a circular dielectric cylinder with a finite-length perfectly conducting metal strip on the cylinder’s lateral surface is considered. The diffraction problem is solved with the use of the method of singular integral equations. The distributions of the surface current on the metal strip are calculated. The patterns of the reflected electromagnetic field are determined from these distributions for various incidence angles of the plane electromagnetic wave. It is shown that the pattern of the diffracted field strongly depends on the angle of the wave incidence on the metal strip.     

Love me Tinder: Untangling emerging adults’ motivations for using the dating application Tinder

Although the smartphone application Tinder is increasingly popular among emerging adults, no empirical study has yet investigated why emerging adults use Tinder. Therefore, we aimed to identify the primary motivations of emerging adults to use Tinder. The study was conducted among Dutch 18–30 year old emerging adults who completed an online survey. Over half of the sample were current or former Tinder users (n = 163). An exploratory factor analysis, using a parallel analysis approach, uncovered six motivations to use Tinder: Love, Casual Sex, Ease of Communication, Self-Worth Validation, Thrill of Excitement, and Trendiness. In contrast to previously suggested, the Love motivation appeared to be a stronger motivation to use Tinder than the Casual Sex motivation. In line with literature on online dating, men were more likely to report a Casual Sex motivation for using Tinder than women. In addition, men more frequently reported Ease of Communication and Thrill of Excitement motives. With regard to age, the motivation Love, Casual Sex and Ease of Communication were positively related to age. Finally, Tinder motivations were meaningfully related to offline encounters with Tinder matches. In sum, the study showed that emerging adults have six primary motivations to use Tinder and that these motivations differ according to one’s age and gender. Tinder should not be seen as merely a fun, hookup app without any strings attached, but as a new way for emerging adults to initiate committed romantic relationships. Notably, the findings call for a more encompassing perspective on why emerging adults use Tinder.     

A multiphase level set formulation for image segmentation using a MRF-based nonsymmetric Student’s-<Emphasis Type="Italic">t</Emphasis> mixture model

This paper proposes a new level set energy function framework in which the Markov random field-based nonsymmetric Student’s-t mixture model (SMM) is incorporated for labelling static images. This framework provides a general strategy by taking the best components of the Bayesian theory and level set technique. Therefore, the proposed segmentation method can bring the topology shape constraints to a statistical finite mixture model. An advantage of this method is that it can overcome the weakness of the conventional level set formulation by filtering out the outliers and stopping at the boundary points. Another feature is that the local relationship among neighbouring pixels is introduced into the prior probability so that the proposed framework is more robust against noise. The method is mainly implemented by modelling the probability density function of the observed data using nonsymmetric SMM. The proposed model has a simplified structure, which effectively reduces the computational complexity. Finally, numerical experiments on various synthetic, real-world images are conducted.     

Application of the Crank–Nicolson FDTD method for analysis of a wideband multi-section hybrid coupler

In this paper the Crank–Nicolson (CN) finite-difference time-domain (FDTD) method is applied for the analysis of a planar wideband hybrid coupler. The proposed method is applied for analysis of transmission lines. Stability issue is investigated for different cases, including lossless and lossy transmission lines. Sufficient conditions for unconditional stability are derived. As a practical problem, a wideband compact hybrid coupler working on 1–6 GHz frequency band is analyzed using the CN-FDTD method. Measurement results show that the proposed coupler provides coupling of 3 ± 0.8 dB with 90° ± 0.85° phase shift and demonstrate the return loss and isolation better than 16 dB over 1–6 GHz. To validate the accuracy of the method, the results of this scheme are compared with measurements and the conditional stable leap-frog (LF) FDTD method. It is observed that using the CN-FDTD, the temporal step-size can be increased up to 1500 time compared with the LF-FDTD method with still good agreement with the measured results.     

300 mm Epitaxy: challenges and opportunities from a wafer manufacturer’s point of view

Results on 300 mm silicon wafer epitaxy according to the 0.18 μm design rule requirements are presented. Wafer uniformity, surface metals, geometry, and thermal stability demonstrate production capabilities. Localized light scattering particles and crystal defects are identified as the largest technological challenge. Preliminary experiments indicate that industry’s requirements can be met. The p/p+ epitaxial wafer is the best candidate to meet the 300 mm cost challenge, as well as the technological requirements for integrated circuit manufacturing.     

Detection of COPD’s auscultative symptoms using higher order statistics in the analysis of respiratory sounds

In this paper we present the method for determination of the specific auscultatory diagnostic signs in patients with chronic obstructive pulmonary disease (COPD), which is based upon the utilization of the polyspectral analysis and the calculation of higher order statistics. The main stages of the method are the calculation and construction of the bicoherence function of the lung sound signal in order to find its maximal value. The visual and numerical estimations of the obtained maximum allow us to conclude the presence or absence in this lung’s audio signal of the artifact, which indicates the pathology. For more accurate results one needs to determine asymmetry coefficient and to perform the estimation of bifrequency corresponding to the maximal value of the bicoherence coefficient. The calculation of skewness and kurtosis coefficients of cross-correlation functions of lung sound signals, which were recorded simultaneously in four channels, allows us to reduce the sensitivity of the method to noise components. Therefore, by analyzing all proposed calculated characteristics and parameters one can conclude the presence or absence of the pathology in this audio signal.     

A 2.488–11.2 Gb/s SerDes in 40 nm low-leakage CMOS with multi-protocol compatibility for FPGA applications

This paper presents the design and Silicon verification of a 2.488–11.2 Gbps multi-standard SerDes transceiver in a 40 nm low-leakage CMOS process. The paper explores the architectural and circuit techniques used to meet the stringent requirements of the high-speed SerDes and to mitigate the performance impact of the low-leakage process. A system modeling approach is described, which is used for optimizing the architectural trade-offs. The transceiver makes use of a low-jitter LC phase locked loop to enable high-reliability system design. The design has 420 fs RJ_rms and consumes 30.1 mW/Gbps at 11.2 Gbps.     

Solutions of the Equations for Space-charge Electron Flow with a Magnetic Field at the Cathode for Beams of Non-uniform Current Density†

After a discussion of the space-charge equations, a solution is given from which the critical conditions are obtained for flows like Brillouin flow but with a magnetic field at the cathode. Results for confined flows are derived; it is shown that, compared with a beam of uniform current density, much more current can be put into a beam of given boundary voltage if the current density increases strongly with radius. Confined ribbon beams are also considered.     

Understanding the effects of the textual complexity on government communication: Insights from China’s online public service platform

While texts are the primary carriers of information for government decision making, few studies have examined the role of textual complexity in government-citizen communication. Using a variety of natural language processing methods, this paper measured textual complexity from the perspectives of word complexity, logical complexity, and abnormal negative emotion based on the textual data of the 1.15 million online messages left by the citizens to government leaders on China’s online public service platform, and explored its impact on government responses. Based on the Double-hurdle model, this paper found that the government response can be composed of two decision-making processes: response-intention, which indicates whether to respond, and response-level, which represents the extent of response. For response-intention decision-making, the simpler the words and logic of the message, the more likely it is to receive a reply from the government. For response-level decision-making, messages with more complex words and logic received a higher level of government response. Abnormal negative emotion in the message significantly reduced the government’s response intention and response level, and the negative effect of abnormal negative emotion on response intention was much greater than on the response level. This study not only helps to understand how the government makes decisions based on textual information, but also has important value for responsive government construction and equalization of government services.