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The purpose of this paper is to illustrate the new technical demands and reliability challenges to printed circuit board (PCB) designs, materials and processes when the transmission frequency increases from Sub-6 GHz in previous generations to millimeter (mm) wave in fifth-generation (5G) communication technology.

The approach involves theoretical analysis and actual case study by various characterization techniques, such as a stereo microscope, metallographic microscope, scanning electron microscope, energy dispersive spectroscopy, focused ion beam, high-frequency structure simulator, stripline resonator and mechanical test.

To meet PCB signal integrity demands in mm-wave frequency bands, the improving proposals on copper profile, resin system, reinforcement fabric, filler, electromagnetic interference-reducing design, transmission line as well as via layout, surface treatment, drilling, desmear, laminating and electroplating were discussed. And the failure causes and effects of typical reliability issues, including complex permittivity fluctuation at different frequencies or environments, weakening of peel strength, conductive anodic filament, crack on microvias, the effect of solder joint void on signal transmission performance and soldering anomalies at ball grid array location on high-speed PCBs, were demonstrated.

The PCB reliability problem is the leading factor to cause failures of PCB assemblies concluded from statistical results on the failure cases sent to our laboratory. The PCB reliability level is very essential to guarantee the reliability of the entire equipment. In this paper, the summarized technical demands and reliability issues that are rarely reported in existing articles were discussed systematically with new perspectives, which will be very critical to identify potential reliability risks for PCB in 5G mm-wave applications and implement targeted improvements.

The purpose of this review is to comprehensively consider the material properties and processing of additive titanium alloy and provide a new perspective for the robotic grinding and polishing of additive titanium alloy blades to ensure the surface integrity and machining accuracy of the blades.

At present, robot grinding and polishing are mainstream processing methods in blade automatic processing. This review systematically summarizes the processing characteristics and processing methods of additive manufacturing (AM) titanium alloy blades. On the one hand, the unique manufacturing process and thermal effect of AM have created the unique processing characteristics of additive titanium alloy blades. On the other hand, the robot grinding and polishing process needs to incorporate the material removal model into the traditional processing flow according to the processing characteristics of the additive titanium alloy.

Robot belt grinding can solve the processing problem of additive titanium alloy blades. The complex surface of the blade generates a robot grinding trajectory through trajectory planning. The trajectory planning of the robot profoundly affects the machining accuracy and surface quality of the blade. Subsequent research is needed to solve the problems of high machining accuracy of blade profiles, complex surface material removal models and uneven distribution of blade machining allowance. In the process parameters of the robot, the grinding parameters, trajectory planning and error compensation affect the surface quality of the blade through the material removal method, grinding force and grinding temperature. The machining accuracy of the blade surface is affected by robot vibration and stiffness.

This review systematically summarizes the processing characteristics and processing methods of aviation titanium alloy blades manufactured by AM. Combined with the material properties of additive titanium alloy, it provides a new idea for robot grinding and polishing of aviation titanium alloy blades manufactured by AM.

This paper aims to better design the resonant tank parameters for LLC resonant converter. And, it is found that under heavy load, the voltage gain is affected by junction capacitors of the primary side switching and the parasitic parameters of the secondary side diodes converted to the primary side, which will cause the voltage gain decreased when the switching frequency decreased.

This paper proposes an optimization parameters design method to solve this problem, which was based on impedance model considering the parasitic parameters of switching devices and diodes.

The effectiveness of the proposed method is verified by impedance Bode plots and experimental results.

From the perspective of impedance modeling, this paper finds the reasons for the insufficient voltage regulation capability of LLC resonant converters under heavy load and finds solutions through analysis.

This study aims to empirically examine the relationship between Internet use and personal privacy risk perceptions, the mediating effect of trust and the moderating effect of satisfaction on that relationship, which is exactly conducive to the practice of personal information protection.

A moderated mediation model will be employed to test the hypothesized relationships using the 2017 Chinese Society Survey data.

The authors find that Internet use positively relates to citizens' risk perceptions toward privacy security, and trust partially mediates the relationship between Internet use and privacy risk perception. In addition, the analysis of moderating effects showed that satisfaction with social life significantly enhances the negative impact on individuals' privacy risk perceptions of interpersonal trust. The positively moderating effect of satisfaction with local governments' work mainly reveals the relationship between interpersonal trust (or institutional trust) and citizens' privacy risk perception. Moreover, satisfaction with Internet platforms positively moderates the relationship between consumer trust and privacy risk perception.

This article contributes to the social risk amplification framework by applying it to the personal privacy information protection field, which was rarely discussed before. It also enriches privacy research by identifying the internal mechanism of how Internet use influences citizens' risk perceptions towards privacy information leakage.

This paper aims to concentrate on recent innovations in flexible wearable sensor technology tailored for monitoring vital signals within the contexts of wearable sensors and systems developed specifically for monitoring health and fitness metrics.

In recent decades, wearable sensors for monitoring vital signals in sports and health have advanced greatly. Vital signals include electrocardiogram, electroencephalogram, electromyography, inertial data, body motions, cardiac rate and bodily fluids like blood and sweating, making them a good choice for sensing devices.

This report reviewed reputable journal articles on wearable sensors for vital signal monitoring, focusing on multimode and integrated multi-dimensional capabilities like structure, accuracy and nature of the devices, which may offer a more versatile and comprehensive solution.

The paper provides essential information on the present obstacles and challenges in this domain and provide a glimpse into the future directions of wearable sensors for the detection of these crucial signals. Importantly, it is evident that the integration of modern fabricating techniques, stretchable electronic devices, the Internet of Things and the application of artificial intelligence algorithms has significantly improved the capacity to efficiently monitor and leverage these signals for human health monitoring, including disease prediction.

This article aims to analyze how gender and decision-making styles of Chief Executive Officers (CEOs) of Small and Medium Enterprises (SMEs) impact the financial performance of the firms they manage.

Data were obtained for 2017 for 185 SMEs in Chile, an emerging economy, including firm information, CEO's sociodemographic characteristics and CEOs' decision-making styles. Generalized Least Squares (GLS) models were estimated to explain the influence of gender and decision-making styles on firm performance, controlling for a series of covariates. To test whether gender moderates the effect of decision-making styles on firm performance, interaction terms were included. Furthermore, models were subject to several robustness procedures, with no significant differences in results.

The authors find evidence of significant relationships for both gender and the avoidant style. Likewise, the authors find evidence of interaction effects between gender and decision-making styles, particularly between gender and the dependent style.

Findings contribute to prior research by analyzing the relationship between CEO gender and SME performance in the context of a Latin American emerging economy; by providing evidence of the impact of decision-making styles on the financial performance of SMEs; and by examining how a specific decision-making style, namely the dependent style, operates differently according to CEO gender, shedding some light on its ambiguous character as described by prior research. For policymakers and authorities, findings indicate the importance of incorporating women to SMEs and supporting their way towards higher management.

Esta investigación analiza cómo el género y los estilos de toma de decisiones de los gerentes generales (CEOs) de las pequeñas y medianas empresas (PYMEs) impactan en el desempeño financiero de las empresas que administran.

Se obtuvieron datos del año 2017 para 185 PYMEs ubicadas en Chile, una economía emergente, incluyendo información de la empresa, así como características sociodemográficas y estilos de toma de decisiones de los gerentes generales. Se estimaron modelos de Mínimos Cuadrados Generalizados (GLS) para explicar la influencia del género y los estilos de toma de decisiones en el rendimiento de la empresa, controlando por una serie de covariables. Para determinar si el género modera el efecto de los estilos de toma de decisiones en el rendimiento de la empresa, se incluyeron términos de interacción. Además, los modelos fueron sometidos a varios procedimientos de robustez, sin encontrar diferencias significativas en los resultados.

Los autores encuentran evidencia de relaciones significativas tanto para el género como para el estilo evitativo. Asimismo, los autores encuentran evidencia de efectos interacción entre el género y estilos de toma de decisiones, particularmente entre el género y el estilo dependiente.

Los hallazgos contribuyen a investigaciones anteriores al analizar la relación entre el género del CEO y el rendimiento de las PYMEs en el contexto de una economía latinoamericana emergente; al proporcionar evidencia del impacto de los estilos de toma de decisiones en el rendimiento financiero de las PYMEs; y al examinar cómo un estilo de toma de decisiones específico, a saber, el estilo dependiente, opera de manera diferente según el género del CEO, esclareciendo su carácter ambiguo tal como ha sido descrito en investigaciones anteriores. Para las autoridades y los responsables de políticas, los hallazgos indican la importancia de incorporar mujeres a las PYMEs y apoyarlas en su ascenso hacia la alta administración.

The vibration of the rails is a significant source of railway rolling noise, often forming the dominant component of noise in the important frequency region between 400 and 2000 Hz. The purpose of the paper is to investigate the influence of the ground profile and the presence of the train body on the sound radiation from the rail.

Two-dimensional boundary element calculations are used, in which the rail vibration is the source. The ground profile and various different shapes of train body are introduced in the model, and results are observed in terms of sound power and sound pressure. Comparisons are also made with vibro-acoustic measurements performed with and without a train present.

The sound radiated by the rail in the absence of the train body is strongly attenuated by shielding due to the ballast shoulder. When the train body is present, the sound from the vertical rail motion is reflected back down toward the track where it is partly absorbed by the ballast. Nevertheless, the sound pressure at the trackside is increased by typically 0–5 dB. For the lateral vibration of the rail, the effects are much smaller. Once the sound power is known, the sound pressure with the train present can be approximated reasonably well with simple line source directivities.

Numerical models used to predict the sound radiation from railway rails have generally neglected the influence of the ground profile and reflections from the underside of the train body on the sound power and directivity of the rail. These effects are studied in a systematic way including comparisons with measurements.

This study aims to examine whether Chinese firms increase their concerns about analysts’ earnings forecasts following the split-share structure reform (SSR) in 2005, which removed trading restrictions on approximately 70% of the shares of listed firms.

Using data from 2002 to 2019, the authors empirically test the association between meeting or beating analysts’ earnings expectations and the implementation of SSR.

The authors find that firms are more inclined to meet analysts’ earnings expectations after the introduction of SSR. Further analysis shows that firms guide analysts to walk their forecasts down by manipulating third-quarter earnings, suggesting enhanced value relevance between analysts’ forecasts and third-quarter earnings management in the postreform period.

The findings reveal an undesirable side effect of SSR and suggest that policymakers and regulators should consider and carefully manage the complex relationships between firms and analysts.

In contrast to prior studies that predominantly focus on the positive effects of the reform, this study reveals the side effects of SSR and provides new evidence on the mechanisms of meeting or beating analysts’ earnings expectations.

The consideration of the substitution phenomenon in the project portfolio selection problem can improve the robustness of project portfolio selection and help enterprises better achieve their strategic objectives. However, the existence of inter-project risk propagation will have a negative impact on project substitution. This paper proposes a new framework for project portfolio selection and constructs a risk propagation model based on strategic objectives to study the impact of risk propagation on substitution in the project portfolio.

The authors first construct a risk propagation model based on strategic objectives to describe the risk propagation between projects. Then the project substitution phenomenon based on risk propagation is put forward, and the calculation method of substitution loss is given. Finally, a robust project portfolio selection framework based on strategic objectives considering risk propagation is constructed.

The analysis of a case study demonstrates that (1) With the increase of risk intensity, the strategic loss of the same project portfolio increases linearly, and under the same risk intensity, the more projects in the portfolio, the stronger the robustness. (2) Considering risk propagation, the effect of project substitution is significantly weakened, and the strategic loss rate of the project portfolio is significantly increased compared with that of a direct attack.

This study is the first to take the project substitution into account in the project portfolio selection process. Moreover, the authors describe inter-project risk propagation and analyze the impact of risk propagation on the project substitution phenomenon. Finally, the authors extend the evaluation index of robustness. This paper puts forward a new way to solve the problem of project portfolio selection.

This study’s main objective is to determine the extent to which social capital and psychological capital can explain differences in career adaptability among higher education students.

The study employed a quantitative approach, utilizing a survey research design. Data were gathered using an online questionnaire completed by 384 fourth-year undergraduate agricultural students in Iran. The inverse square root and multistage sampling methods were used to determine the sample size. The partial least squares-structural equation modelling (PLS-SEM) method examined the associations between latent variables.

The results suggest that social and psychological capital significantly influence the career adaptability of agricultural students, highlighting their significance in enhancing career adaptability. Moreover, psychological capital positively mediates the relationship between social capital and career adaptability.

Agricultural higher education institutions must focus on developing students' social and psychological capital to cultivate career adaptability in agricultural students. Agricultural higher education institutions, for example, should help students develop soft skills.

This study offers novel insights into the significance of individual resources, such as social and psychological capital, in enhancing the career adaptability of students. In addition, the key contribution of this study is the researchers' empirical evidence that multiple career resources are interconnected (social capital, career adaptability, and psychological capital).