Study of haze emission efficiency based on new co-opetition data envelopment analysis

As haze intensifies in China, controlling haze emission has become the country's top priority for environmental protection. Because haze moves across different regions, it is necessary to develop a data envelopment analysis (DEA) model underpinned by both competition and cooperation to evaluate the haze emission efficiency in different provinces. This study innovatively adopts the spatial econometrics to construct the co-opetition matrices of Chinese provinces, then builds the co-opetition DEA model to evaluate the haze emission efficiency of them, and finally uses the haze data of 2015 as an example to assess the applicability of the model. The results of the study include the following: First, compared with the traditional CCR (A. Charnes & W. W. Cooper & E. Rhodes) model, this study constructs the co-opetition DEA cross-efficiency model that integrates haze's feature of cross-border moving; thus, it is more in line with the reality of haze emission and movement. Second, compared with the efficiency value gained from the CCR model, the haze emission efficiency values for Tianjin and Guangdong, two decision-making units, register greater variance when using the DEA model. The reason might lie in that they have a different spatial transportation relationship with their surrounding provinces. Third, the haze emission efficiency of provinces, according to the evaluation based on the co-opetition DEA method, varies greatly: Those with high efficiency are mostly inland provinces with slow economic growth and adverse climatic conditions, whereas many of the provinces with low efficiency are located in the relatively prosperous East China. The specific co-opetition DEA model constructed in this study enriches the research on the DEA model, which can be applied to the emission efficiency evaluation of similar pollutants around the world and can contribute empirical support to the haze reducing efforts of the government with its empirical results.     

双层复合衬砌隧洞运行安全预警监控指标研究

双层复合衬砌结构是一种新型隧洞衬砌结构型式,其外衬承受外部水土压力,内衬承受内水压力,体现了"结构联合、功能独立"的新型输水隧洞设计理念,目前该衬砌型式已成功应用到我国北方某输水工程中,如何确定双层复合衬砌隧洞安全预警监控指标是工程运行管理的重点和难点。本文基于以往研究成果,提出了工程结构监控指标及监控阈值确定的统一技术路径;根据双层复合衬砌结构受力特点,开展可能破坏模式分析;基于破坏模式与监测量的敏感性分析,提出层间渗压作为双层复合衬砌隧洞结构核心监控指标,内衬处的钢筋计测值以及外衬处的测缝计测值作为辅助监控指标,为双层复合衬砌隧洞安全运行提供借鉴和参考。     

Polarity Effect and Electromagnetic Radiation of Partial Discharge Accompanying Growth of Electrical Tree

We have investigated the characteristics of radiated electromagnetic (EM) waves from positive and negative partial discharges (PD) in epoxy resin and cross‐linked polyethylene. We found that there is a correlation among the EM level from PD, the positive PD current, and electrical trees. Therefore, the growth of an electrical tree produces a lot of positive PD. We have also investigated the characteristics of the frequency region of EM waves from PD in air, insulating oil, and liquid epoxy in addition to the above insulators. EM waves were detected in the frequency region of 40 MHz to 300 MHz from positive and negative PD in epoxy resin and cross‐linked polyethylene. EM waves were also detected in the frequency region of 40 MHz to 150 MHz from positive and negative PD in air. In the case of insulating oil and liquid epoxy, EM waves were detected in the frequency regions of 40 MHz to 150 MHz from positive PD, and 40 MHz to 250 MHz from negative PD. The frequency region differed depending on the material and the discharge polarity. Our investigation indicates that the cause is differences in electric field strength at the time of PD occurrence.     

高集成度射频收发器的差分正交调制解调测试与工程实现

针对高集成度射频收发器(AD9361)实现差分正交调制解调(DQPSK)收发过程中存在的工程实现问题,采用理论分析与硬件平台实现相结合的方法测试AD9361,验证DQPSK调制解调;先通过Serial Peripheral Interface(SPI)接口测试AD9361自发自收,采用点积叉积方法实现了DQPSK的调制解调;配置AD9361过程中,通过测试定位初始化后AD9361输出端无波形、通过示波器观察发现AD9361发射与接收本振时域波形扭曲、频谱仪观察AD9361输出端谐波分量严重、DQPSK解调时发射本振与接收本振存在随机相位误差4个疑难问题,分别通过采用降低SPI时钟频率为10 MHz、AD9361芯片的系统时钟更改设置为40 MHz、初始化过程中输出端频率设置为1.4 GHz、DQPSK的解调采用点积叉积方式进行解调4种方法予以解决;实验结果表明4个相关问题解决效果良好,所实现的DQPSK收发性能可靠。     

A study on the thermoelectric properties of ALD-grown aluminum-doped tin oxide with respect to nanostructure modulations

The thermoelectric properties of aluminum-doped tin oxide (ATO) thin films synthesized by thermal atomic layer deposition (ALD) were studied with respect to the aluminum concentration. The overall aluminum content in each layer was modulated by adjusting the relative number of tin oxide (SnO₂) and aluminum oxide (Al₂O₃) growth cycles, where a sequential process involving n cycles of SnO₂ growth followed by 1 cycle of Al₂O₃ deposition was performed (building up a super-cycle). The electrical conductivity (620 S/cm), free carrier concentration (1.23x10²¹ cm^-3), and power factor (0.49 mW/K²m) increase until their maximum values are reached when the Al content is approximately 1.50 at% of the cations, and decrease as more Al is added in. On the other hand, the Seebeck coefficient decreases monotonically as the Al content increases up to about 2.88 at%, and begins to increase with further Al doping. Here the thermoelectric efficiency is therefore determined primarily by the free carrier concentration, while the Seebeck coefficient appears to be influenced by the overall crystal structure.     

Tailoring the electron-blocking layer by addition of YSZ to Ba-containing anode for improvement of ceria-based solid oxide fuel cell

The in-situ fabrication of an electron-blocking layer between the Ba-containing anode and the ceria-based electrolyte is an effective approach in suppressing the internal electronic leakage in ceria-based solid oxide fuel cell (SOFC). To improve the thickness of the electron-blocking layer and to research the effect of the layer thickness on the improvement of SOFC, a Ba-containing compound (0.6NiO-0.4BaZr_0.1Ce_0.7Y_0.2O_3-δ) modified by Y stabilized zirconia (YSZ) was employed as a composite anode in this research. SEM analyses demonstrated that the thickness of the interlayer can be simply controlled by regulating the proportion of YSZ at anode. The in-situ formed interlayer in the cell with the anode modified by 20?mol% YSZ possesses a thickness of 0.9?µm which is more suitable for the cell achieving an enhanced performance.     

Experimental study of the combustion characteristics of methanol‐gasoline blends pool fires in a full‐scale tunnel

The combustion characteristics of methanol‐gasoline blends pool fires were studied in a series of full‐scale tunnel experiments conducted with different methanol and gasoline blends. The parameters were measured including the mass loss rate, the pool surface temperature, the fire plume centerline temperature, the ceiling temperature, the smoke layer temperature profile, the flame height, and the smoke layer interface height. The gasoline components were analyzed by GC‐MS. The effects of azeotropism on the combustion characteristics of the different blends were discussed. On the basis of the results of the fire plume centerline temperature, the ceiling temperature, and the flame height, it shows that the tunnel fire regime gradually switches from fuel controlled to ventilation controlled with increasing gasoline fractions in the blends. The fire plume can be divided into 3 regions by the fire plume centerline temperature for the different blends. The N‐percentage rule to determine the smoke layer interface height is found to be applicable for tunnel fires with different blends for N = 26.     

Enhanced microwave absorbance of oxidized SiCf/AlPO4 composites via the formation of a carbon layer on the SiC fibre surface

A single-layer radar-absorbing structure active in the X-band (8.2?GHz to 12.4?GHz) was demonstrated by blending SiC fibres with an AlPO₄ matrix material. The as-prepared SiC_f/AlPO₄ composites were oxidized at 1273?K for several hours to investigate the effects of oxidation on the dielectric and wave-absorbing properties. Scanning and transmission electron microscopy were used to characterize the morphology and microstructure of the composites. The AlPO₄-SiO₂ solid solution during oxidation promoted the formation of a complete carbon layer on the SiC fibre surface. The real and imaginary parts of the SiC_f/AlPO₄ composites increased from 4.2–4.4 to 5.9–7.1 and from 0.08–0.2 to 3.9–5.2, respectively, with increasing oxidation time from 0 to 10?h, respectively. When the thickness of the composites increased from 2.9?mm to 3.3?mm, the wave-absorbing property noticeably improved due to the formation of a carbon layer on the SiC fibre surface after oxidation.     

Multilayer assembly of ionic starches on old corrugated container recycled cellulosic fibers

In this study, old corrugated container recycled fibers were treated with polyelectrolyte multilayers consisting of biopolymer cationic starch with two degrees of substitution (DS) each in combination with one anionic starch. Pulp zeta potential, paper strength and the thin layer ellipsometry technique were applied to examine the influence of cationic starch DS on the formation of polyelectrolyte multilayers. The results indicated a significant interaction between the DS of cationic starch and the number of ionic starch layers formed. When low‐DS cationic starch was used, the pulp zeta potential and the paper strength increased significantly in assembling the first cationic layer. However, in depositing high‐DS cationic starch a greater zeta potential and a stronger influence on the paper strength were observed with a larger number of starch layers. This was confirmed by thin layer ellipsometry when a greater thickness of multilayers was achieved by employing high‐DS cationic starch to form a higher number of layers. © 2017 Society of Chemical Industry     

Effect of processing parameters on electropolishing of commercially pure Ti in an alcohol-based electrolyte

Commercially pure titanium (Cp-Ti) foils were electropolished by using a DC power source in an alcohol-based electrolyte. The influences of applied voltage, processing time, electrolyte temperature and agitation on surface morphology and surface oxygen content were investigated and are reported. Results showed that optimum surface finish in this electrolyte can be achieved at applied voltages in the range of 35–75?V with shorter times at higher applied voltage. Also, increasing electrolyte temperature efficiently accelerates the electropolishing process and gives better surface finishes with respect to that achieved with lower electrolyte temperature at short processing times. Oxygen content of the surface varies with processing parameters and directly affects the surface morphology. The smoothest surface finish was always accompanied by the lowest oxygen content on the surface.