Search

Exploring the problem of teaching quality monitoring and evaluation from the perspective of educational balance can help educators and policy makers discover educational inequality problems, thereby promoting fair allocation of educational resources and opportunities. In light of this, this study attempts to research teaching quality monitoring and evaluation from the perspective of educational balance. At first, the mechanism of promoting educational balance by information technology was expounded, and the principle and necessity of a comprehensive assessment based on the evaluation results of different evaluators were explained. Then, this study innovatively introduced the whitening weight function (WWF)-grey evaluation model into the conventional grey clustering evaluation, calculated the unit comprehensive clustering coefficients of the indexes of teaching quality evaluation from the perspective of educational balance, and gave fair, accurate, and effective evaluations. After that, the grey GM (1,1) model was applied to the prediction of teaching quality improvement effect, the future trend of teaching quality changes was predicted based on history data, and the results provided references for teaching reform and educational decision-making. At last, experimental results verified the validity of the proposed method. [ABSTRACT FROM AUTHOR]

In order to analyze the characteristics of coal quality composition of Shanxi Formation 2# in Ningwu Coal Mine, Shanxi Province, the content characteristics, occurrence state and enrichment mechanism of the elements in the coal were discussed. X-ray fluorescence spectroscopy (XRF) is used to determine the content of major elements in coal and gangue, X-ray diffraction (XRD) is used to analyze the mineral composition of coal, scanning electron microscope + energy spectrum (SEM-EDX) is employed to observe the morphological characteristics of minerals, the inductively coupled plasma mass spectrometer (ICP-MS) is used to determine the content of trace elements in coal and gangue, and the progressive chemical extraction (SCEP) is employed to determine the presence of trace elements in coal. Experimental studies have shown that the minerals in Shanxi Formation 2# coal are mainly clay minerals and calcite. The clay minerals are mainly kaolinite, which is derived from terrigenous clastic materials. Calcite is a metagenetic mineral, which is precipitated in the circulating water of the cracks or voids in the coal. The trace elements Li, Cu, Ga, In, and Hf are slightly enriched, and Zr and Nb are enriched. There is a positive correlation between some trace elements and ash, which indicates that these trace elements are mainly contained in inorganic minerals, and some trace elements have no obvious or negative correlation with ash, which indicates that in addition to inorganic minerals, trace elements are also present in organic matter. [ABSTRACT FROM AUTHOR]

In heterogeneous networks (HetNets), energy saving is vital for a sustainable network development. Many techniques, such as spectrum allocation, network planning, etc., are used to improve the network energy efficiency (EE). In this paper, micro BSs utilizing cell range expansion (CRE) and spectrum allocation are considered in multi-channel heterogeneous networks to improve EE. Hotspot region is assumed to be covered by micro BSs which can ensure that the hotspot capacity is greater than the average demand of hotspot users. The expressions of network energy efficiency are derived under shared, orthogonal and hybrid subchannel allocation schemes, respectively. Particle swarm optimization (PSO) algorithm is used to solve the optimal ratio of subchannel allocation in orthogonal and hybrid schemes. Based on the results of the optimal analysis, we propose three service control strategies on the basis of large-scale user behaviors, i.e., adjust micro cell rang expansion (AmCRE), adjust micro BSs density (AmBD) and adjust micro BSs transmit power (AmBTP). Both theoretical and simulation results show that using shared subchannel allocation scheme in AmBD strategies can obtain maximal EE with a very small area ratio. Using orthogonal subchannel allocation scheme in AmCRE strategies can obtain maximal EE when area ratio is larger. Using hybrid subchannel allocation scheme in AmCRE strategies can obtain maximal EE when area ratio is large enough. No matter which service control strategy is used, orthogonal spectrum scheme can obtain the maximal hotspot user rates. [ABSTRACT FROM AUTHOR]

Straw returning is an important factor in taking full advantage of the resources in the agricultural ecosystem. In this study, a field study was conducted to compare the greenhouse gas (GHG) emissions and soil organic carbon (SOC) under different rice (R) and wheat (W) straw returning modes (RDI, rice straw returned in wheat season and WDI, wheat straw returned in rice season) and ditch burying with different depths, viz., 20 cm (RD20 and WD20), 40 cm (RD40 and WD40) and 60 cm (RD60 and WD60) in a wheat-rice rotation system. Ditch burying treatments significantly decreased GHG emissions compared with RDI, while RD40 and RD60 had no significant difference in the total global wanning potential (GWP) compared to RCK (no rice straw returning). The SOC and the carbon pool management index (CPMI) with RD, (WDi) were significantly higher than those with the other four treatments in the initial stage after straw returning. However, the difference in SOC and CPMI between RDI (WDI) and the other four treatments exhibited a decreasing trend. In addition, ditch burying treatments exhibited no significant difference in the crop yield in relation to CK. This result suggests that in eastern China, straw ditch burying should be a better approach to reducing GHG emissions and improving soil carbon quality without affecting the crop yield. [ABSTRACT FROM AUTHOR]

This paper analyzes the optimal user density and power allocation for Device-to-Device (D2D) communication underlaying cellular networks on multiple bands with the target of maximizing the D2D transmission capacity. The entire network is modeled by Poisson point process (PPP) which based on stochastic geometry. Then in order to ensure the outage probabilities of both cellular and D2D communication, a sum capacity optimization problem for D2D system on multiple bands is proposed. Using convex optimization, the optimal D2D density is obtained in closed-form when the D2D transmission power is determined. Next the optimal D2D transmission power is obtained in closed-form when the D2D density is fixed. Based on the former two conclusions, an iterative algorithm for the optimal D2D density and power allocation on multiple bands is proposed. Finally, the simulation results not only demonstrate the D2D performance, density and power on each band are constrained by cellular communication as well as the interference of the entire system, but also verifies the superiority of the proposed algorithm over sorting-based and removal algorithms. [ABSTRACT FROM AUTHOR]

ZnO thin film-based surface acoustic wave (SAW) devices were fabricated on Si, glass and polyimide (PI) substrates, and their microfiuidic performances were compared. The Rayleigh and Sezawa mode waves were observed from the ZnO/Si devices, the Rayleigh and Lamb modes from the ZnO/PI, and only the Rayleigh mode from the ZnO/glass devices. The ZnO/Si devices have the best performance with the highest acoustic streaming velocity of about 10 cra/s and the shortest particle concentration time of less than 10 sec. The ZnO/glass SAW devices deliver comparable performances to that on Si substrate, while the ZnO/PI devices perform not as good as the devices on other two types of substrates due to the large acoustic attenuation, but still can deliver a streaming velocity up to 1.0 cm/s and reasonable particle concentration function with a particle concentration time of ~70 sec. Owing to its low cost, easy fabrication and compatible with traditional glass-based biochemical analysis systems, ZnO/glass SAW device is believed to have better potential for lab-on-a-chip application. [ABSTRACT FROM AUTHOR]

Taking the framing theory as a guide, this thesis analyzes the media reproduction of 7.23 motor car accident. Selecting the related reports of the People's Daily, Southern Metropolis Daily, people.com.cn and iFeng.com as study samples, it has made comparative analysis from the two aspects of media technical attributes and operation properties, and found out five media frames, including the frame of accident development, the frame of emergency response, the frame of crisis public relations, the frame of reason and responsibility, and the frame of humanistic concern. With the help of computer technology, this thesis has completed the process of sample collection, data statistics and processing, and also the comprehensive analysis of the media report framework, number of reports, information sources, news sources and reports tune, and studied the coverage characteristics and rules of different news media. [ABSTRACT FROM AUTHOR]

Conventional optimization designs of wireless networks mainly focus on spectral efficiency (SE) as a performance metric. However, as diverse media services are emerging, a green wireless network, which not only meets the quality of experience (QoE) requirements for users and also improves energy efficiency (EE), is the most appropriate solution. In this paper, we firstly propose the unit QoE per Watt, which is termed QoE efficiency (QEE), as a user-oriented metric to evaluate EE for wireless networks. We then analyze which is the kind of wireless resource given priority to use under different scenarios to obtain an acceptable QEE. Particularly, power, delay and data-rate related to QoE are separately addressed for several typical services, such as file download, video stream and web browsing services. Next, the fundamental tradeoffs are investigated between QEE and SE for wireless networks. Our analytical results are helpful for network design and optimization to strike a good balance between the users perceived QoE and energy consumption. [ABSTRACT FROM AUTHOR]

Based on wideband precoding (WBP) in the multiple-input multiple-output orthogonal frequency division multiplexing system, an adaptive nonuniform codebook is presented in this paper. The relationship between the precoder distribution and spatial correlation is analyzed at first. A closed-form expression based on overlapped isosceles triangles is proposed as an approximation of the precoder distribution. Then, the adaptive codebook design is derived with the approximate distribution to minimize quantization errors. The capacity and bit error rate performance demonstrate that the adaptive codebook with WBP outperforms the conventional fixed uniform codebook. [ABSTRACT FROM AUTHOR]

Precoding in the multiple-input multiple-output orthogonal frequency division multiplexing system is investigated. In conventional wideband precoding (WBP), only one precoder, obtained from the decomposition of the subcarrier independent channel matrix, is used for all subcarriers. With an investigation of the relationship between the subcarrier independent channel matrix and the temporal/frequency channels, an improved WBP scheme is proposed for practical scenarios in which a part of subcarriers are allocated to a user. The improved WBP scheme is a generalized scheme of which narrow-band precoding and conventional WBP schemes are special modes. Simulation results demonstrate that the improved WBP scheme almost achieves the optimum performance of a single precoder and outperforms the conventional WBP scheme in terms of the bit error ratio and ergodic capacity with slight complexity increase. The largest advantage of the improved WBP scheme on signal-tonoise ratio in simulation results is over 2.1 dB. [ABSTRACT FROM AUTHOR]

We consider a two-hop multiple-relay network implemented with opportunistic decode-and-forward cooperative strategy, where the first hop and second hop links experience different fading (Rayleigh and Rician). We derive the exact expressions of end-to-end outage probability and analyze the approximate results in high signal-to-noise ratio region. The analysis shows that the same diversity order can be achieved even in different mixed fading environments. Simulation results are provided to verify our analysis. [ABSTRACT FROM AUTHOR]

The article discusses the result of a study which examined neurotransmitter regulation of extracellular signal-regulated kinase 1/2 (ERK 1/2) expression after subarachnoid hemorrhage (SAH). It was found that apoptosis occurred in the rat cortex and ERK 1/2 was expressed before apoptosis. The paper also suggests that acetylcholine chloride treatment may reduce apoptotic cells following SAH, possibly by downregulating the expression of ERK 1/2.

The article presents a study which analyzed calcitonin gene-related peptide (CGRP) and endothelin receptor A after subarachnoid hemorrage in rabbits. The analysis was made using immunohistochemistry. It explains that many studies have shown that intense vasoconstriction occurs when endothelin-1 combines with endothelin receptor A. The results suggest that CGRP and endothelin receptor A expressions actively changed in brain vessels and tissues after subarachnoid hemorrhage.