Some New Concepts of Shape Memory Effect of Polymers

In this study some new concepts regarding certain aspects related to shape memory polymers are presented. A blend of polylactic acid (PLA) (80%) and polybutylene succinate (PBS) (20%) was prepared first by extrusion, then by injection molding to obtain the samples. Tensile, stress-relaxation and recovery tests were performed on these samples at 70 °C. The results indicated that the blend can only regain 24% of its initial shape. It was shown that, this partial shape memory effect could be improved by successive cycles of shape memory tests. After a fourth cycle, the blend is able to regain 82% of its shape. These original results indicated that a polymer without (or with partial) shape memory effect may be transformed into a shape memory polymer without any chemical modification. In this work, we have also shown the relationship between shape memory and property memory effect. Mono and multi-frequency DMA (dynamic mechanical analyzer) tests on virgin and 100% recovered samples of polyurethane (PU) revealed that the polymer at the end of the shape memory tests regains 100% of its initial form without regaining some of its physical properties like glass transition temperature, tensile modulus, heat expansion coefficient and free volume fraction. Shape memory (with and without stress-relaxation) tests were performed on the samples in order to show the role of residual stresses during recovery tests. On the basis of the results we have tried to show the origin of the driving force responsible for shape memory effect

Interleaved High Step-up DC-DC Converter with Diode-Capacitor Multiplier Cell and Ripple-Free Input Current

In this paper interleaving and switched-capacitor techniques are used to introduce a high step-up DC-DC converter for renewable energy systems application. The proposed converter delivers high voltage gain without utilizing transformer or excessive duty cycle and features ripple-free input current which results in lower conduction losses and decreased electromagnetic interference (EMI). Lower output capacitance is another advantage of proposed converter, leading to smaller size and lower cost. Furthermore lower voltage stress on switches allows the utilization of switches with low resistance. Simulation results verify the performance of suggested converter

An Overview of the Epidemiologic, Diagnostic and Treatment Approaches of COVID-19: What do We Know?

Background: In late December 2019, a new infectious respiratory disease (COVID-19) was reported in a number of patients with a history of exposure to the Huanan seafood market in China. The World Health Organization officially announced the COVID-19 pandemic on March 11, 2020. Here, we provided an overview of the epidemiologic, diagnostic and treatment approaches associated with COVID-19. Methods: We reviewed the publications indexed in major biomedical databases by December 20, 2020 or earlier (updated on May 16, 2021). Search keywords included a combination of: COVID-19, Coronavirus disease 2019, SARS-CoV-2, Epidemiology, Prevention, Diagnosis, Vaccine, and Treatment. We also used available information about COVID-19 from valid sources such as WHO. Results and Conclusion: At the time of writing this review, while most of the countries authorized COVID-19 vaccines for emergency use starting December 8, 2020, there is no a definite cure for it. This review synthesizes current knowledge of virology, epidemiology, clinical symptoms, diagnostic approaches, common treatment strategies, novel potential therapeutic options for control and prevention of COVID-19 infection, available vaccines, public health and clinical implications

Interleaved High Step-up DC-DC Converter with Diode-Capacitor Multiplier Cell and Ripple-Free Input Current

In this paper interleaving and switched-capacitor techniques are used to introduce a high step-up DC-DC converter for renewable energy systems application. The proposed converter delivers high voltage gain without utilizing transformer or excessive duty cycle and features ripple-free input current which results in lower conduction losses and decreased electromagnetic interference (EMI). Lower output capacitance is another advantage of proposed converter, leading to smaller size and lower cost. Furthermore lower voltage stress on switches allows the utilization of switches with low resistance. Simulation results verify the performance of suggested converter

Water Reflections in the Mirror of the Mind: A Phenomenological Analysis of the Semnan Water Market

The implementation of a water market scheme in Semnan province, as a novel approach to water resource management, has provided unique opportunities to enhance efficiency and create balance in water resource utilization. However, despite the short time since its launch, the scheme has not garnered significant adoption. This research, employing a phenomenological approach, delves into the lived experiences of key stakeholders in Semnan province to gain a comprehensive understanding of the challenges and opportunities within the water market. A phenomenological analysis of data obtained from in-depth interviews with 24 key stakeholders led to the identification of 764 initial codes and semantic units, which were subsequently categorized into 126 primary themes. These primary themes were ultimately grouped into five core themes: motivations and factors influencing the formation and development of the water market, vulnerabilities and obstacles to sustainable water market development, requirements for inclusive water governance in the market era, innovative mechanisms and solutions for improving water market performance, and the consequences and outcomes of the water market. The findings include 29 motivators and drivers for the water market launch, categorized into 5 groups; approximately 23 challenges, obstacles, and vulnerabilities of the Semnan water market; 25 items related to reforming the governance system at the provincial level, encompassing dimensions such as stakeholder participation, capacity, financing, about 15 mechanisms to overcome existing challenges and obstacles; and finally, 19 positive and 15 negative consequences of the water market launch, which are analyzed in the presented model and findings section

Speech emotion recognition based on SVM and KNN classifications fusion

Recognizing the sense of speech is one of the most active research topics in speech processing and in human-computer interaction programs. Despite a wide range of studies in this scope, there is still a long gap among the natural feelings of humans and the perception of the computer. In general, a sensory recognition system from speech can be divided into three main sections: attribute extraction, feature selection, and classification. In this paper, features of fundamental frequency (FEZ) (F0), energy (E), zero-crossing rate (ZCR), fourier parameter (FP), and various combinations of them are extracted from the data vector, Then, the principal component analysis (PCA) algorithm is used to reduce the number of features. To evaluate the system performance. The fusion of each emotional state will be performed later using support vector machine (SVM), K-nearest neighbor (KNN), In terms of comparison, similar experiments have been performed on the emotional speech of the German language, English language, and significant results were obtained by these comparisons

Role of Consumption Emotions Mediate Perceived Service Fairness to the Service Satisfaction and Its Impact on Customers’ Behavioral Intentions

Considering that customers’ emotions toward received services are evaluated in light of fairness and equity theory, the purpose of this study is to investigate the effect of customers’ perceptions and emotions of received services on their behavioral intentions. Data were collected from 329 questioners that were distributed among Mellat bank customers, and hypotheses and the conceptual model were analyzed based on the data collected through structural equation modeling in AMOS 18. Results showed that three dimensions of interactional, procedural, and distributive justice affected customers’ emotions (negative and positive) and satisfaction. Customers’ emotions were also found to be having a mediating role in the relationship between perceptions of fairness (except procedural fairness) and customer satisfaction. The other results are the effect of customer satisfaction on behavioral intentions (repeat purchases and Word-of-mouth advertising). Finally, the study suggests some practical solutions and future research topics