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排序方式: 共有321条查询结果,搜索用时 15 毫秒
41.
This study examined impact of a social media networks course on student use of SNSs performance. Moreover, it examined the associations among course design, course materials, learning experiences and a social media networks course. Survey instrument is used to examine the relationships in the proposed model. A total of 380 questionnaires have been collected from students at the University of Jordan who studied the social media networks course. A structural equation modelling approach based on AMOS 20.0 statistical software is used to study the causal relationships and test the hypotheses between the observed and latent constructs in the proposed research model. The analysis results revealed that course materials and learning experiences directly, positively and significantly impacted the social media networks course, which in turn had a significant impact on students’ use social networks sites performance. Course design, however, did not impact the social media networks course. Our findings have important implications as we demonstrated the validity of the joint two different models and provide information about impact of studying social media networks course on students’ academic performance.  相似文献   
42.
The purpose of this study is to assess the effectiveness of the Texas “Closing the Gaps by 2015” plan to increase Hispanic enrollment into and graduation from institutions of higher education. This study uses Interrupted Time Series with Comparison Group to analyze 26 years of student cohorts in Texas universities. Controlling for historical enrollment and graduation growth as well as population growth, the results show that Hispanic college enrollment significantly increased as a result of the plan, but graduation did not. Several recommendations are offered for those states that wish to emulate Texas policies of increasing college enrollment and graduation of Hispanics.  相似文献   
43.
Measurement of optical properties of skin is an expanding and growing field of research. Recent studies have shown that the biological tissue, especially skin, changes the polarization state of the incident light. Using this property will enable the study of abnormalities and diseases that alter not only the light intensity but also its polarization state. In this paper we report an experimental study for measuring changes of polarization state of the light scattered from a phantom similar to a sample model of scattering skin. Using the notation of Stokes vector for the polarized light and Mueller matrix for the sample with its polarization properties, we have shown that some elements of the matrix were particularly sensitive to the changes of the polarization-altering physical properties of the scatterers within the phantom.   相似文献   
44.
This paper describes the fabrication of a waveguide and the analysis of its polarization characteristics by applying light-emitting diode (LED) pumping lights to its surface. By using double tubed coaxial line (DTCL) microwave plasma chemical vapor deposition (MPCVD) equipment, an a-Si:H/SiN multilayer waveguide was fabricated whose thickness could be controlled at nanometer order. The main structural material of the waveguide sample consisted of a combination of layers of amorphous silicon hydrogen and silicon nitrate. Once the sample was ready, another major objective of the experiment was to analyze the polarization characteristics of the fabricated waveguide. The idea of the experiment was to analyze how the waveguide reacts when three types of LED (blue, yellow, and red) are radiated onto its surface. The results showed that the fabrication of the a-Si:H/SiN sample is successful. Most effective transmission results, which accord with the polarization characteristics analysis, were obtained.  相似文献   
45.
Speaker variability is an important source of speech variations which makes continuous speech recognition a difficult task. Adapting automatic speech recognition (ASR) models to the speaker variations is a well-known strategy to cope with the challenge, Almost all such techniques focus on developing adaptation solutions within the acoustic models of the ASR systems. Although variations of the acoustic features constitute an important portion of the inter-speaker variations, they do not cover variations at the phonetic level. Phonetic variations are known to form an important part of variations which are influenced by both micro-segmental and suprasegmental factors. Inter-speaker phonetic variations are influenced by the structure and anatomy of a speaker's articulatory system and also his/her speaking style which is driven by many speaker background characteristics such as accent, gender, age, socioeconomic and educational class. The effect of inter-speaker variations in the feature space may cause explicit phone recognition errors. These errors can be compensated later by having appropriate pronunciation variants for the lexicon entries which consider likely phone misclassifications besides pronunciation. In this paper, we introduce speaker adaptive dynamic pronunciation models, which generate different lexicons for various speaker clusters and different ranges of speech rate. The models are hybrids of speaker adapted contextual rules and dynamic generalized decision trees, which take into account word phonological structures, rate of speech, unigram probabilities and stress to generate pronunciation variants of words. Employing the set of speaker adapted dynamic lexicons in a Farsi (Persian) continuous speech recognition task results in word error rate reductions of as much as 10.1% in a speaker-dependent scenario and 7.4% in a speaker-independent scenario.  相似文献   
46.
There is an ongoing debate over the activities of brands and companies in social media. Some researchers believe social media provide a unique opportunity for brands to foster their relationships with customers, while others believe the contrary. Taking the perspective of the brand community building plus the brand trust and loyalty literatures, our goal is to show how brand communities based on social media influence elements of the customer centric model (i.e., the relationships among focal customer and brand, product, company, and other customers) and brand loyalty. A survey-based empirical study with 441 respondents was conducted. The results of structural equation modeling show that brand communities established on social media have positive effects on customer/product, customer/brand, customer/company and customer/other customers relationships, which in turn have positive effects on brand trust, and trust has positive effects on brand loyalty. We find that brand trust has a fully mediating role in converting the effects of enhanced relationships in brand community to brand loyalty. The implications for marketing practice and future research are discussed.  相似文献   
47.
In this paper, a novel approach for the design of an indirect adaptive fuzzy output tracking excitation control of power system generators is proposed. The method is developed based on the concept of differentially flat systems through which the nonlinear system can be written in canonical form. The flatness-based adaptive fuzzy control methodology is used to design the excitation control signal of a single machine power system in order to track a reference trajectory for the generator angle. The considered power system can be written in the canonical form and the resulting excitation control signal is shown to be nonlinear. In case of unknown power system parameters due to abnormalities, the nonlinear functions appearing in the control signal are approximated using adaptive fuzzy systems. Simulation results show that the proposed controller can enhance the transient stability of the power system under a three-phase to ground fault occurring near the generator terminals.  相似文献   
48.
Cardiovascular diseases (CVD) are recognized as major mortality causes and imposes tremendously heavy socio-economic burden worldwide. A vast variety of risk factors have been introduced in the literature known to enhance the incidence of CVD, such as hyperlipidemia. Therefore in order to make an accurate clinical decision it is essential to have appropriate reference ranges for lipids and lipoprotein particles in a particular population. Healthy female (n = 601) and male (n = 617) cases were randomly selected according to certain exclusion criteria from individuals visiting the major University hospital clinics situated in different part of Ahvaz city, Iran, from June 2010 to December 2010. Fasting blood samples (10 ml) were collected and analyzed for total cholesterol, total triglyceride and HDL-C employing enzymatic assays of CHOD-PAP, GPO-PAP and homogenous methods respectively. The samples were obtained such to include the ethnic populations of Persian, Arab. Lore leaving in this city. The data were analyzed statistically by SPSS-18 software. The obtained results were analyzed then age ethnic-wise and reference ranges (mean ± 1SD) were calculated. Remarkable differences between the obtained results for our population with other nations were seen. Also ethnic difference for HDL-C among our cases was noted. The observed significant differences among different nations and ethnicities emphasizes the need for nation-specific, local reference ranges for lipids and lipoproteins particles, to be established.  相似文献   
49.
Average-ability students often do not take full advantage of learning in mixed-ability groups because they hardly engage in the group interaction. This study examined whether structuring collaboration by group roles and ground rules for helping behavior might help overcome this participatory inequality. In a plant biology course, heterogeneously grouped fourth-grade boys (n=164) were randomly assigned to a structured collaboration condition or an unconstrained comparison condition. Results indicated positive effects of structured collaboration on average-ability students’ achievement, motivation, and contribution to the group interaction. Another positive result was that structuring collaboration did not lower the scores of the high and low-ability students on these measures.  相似文献   
50.
Sulfide-containing waste streams are generated by a number of industries. It is emitted into the environment as dis- solved sulfide (S2- and HS-) in wastewaters and as H2S in waste gases. Due to its corrosive nature, biological hydrogen sulfide removal processes are being investigated to overcome the chemical and disposal costs associated with existing chemically based removal processes. The nitrogen and sulfur metabolism interacts at various levels of the wastewater treatment process. Hence, the sulfur cycle offers possibilities to integrate nitrogen removal in the treatment process, which needs to be further optimized by appropriate design of the reactor configuration, optimization of performance parameters, retention of biomass and optimization of biomass growth. The present paper reviews the biotechnological advances to remove sulfides from various environments.  相似文献   
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