Preparation and properties of magnesium oxysulfate cement and its application as lost circulation materials

Loss of drilling fluids in large porous and fractured zones inevitably up-regulates the overall cost of drilling.As a type of acid-soluble cement,magnesium oxys...     

Optimal low-complexity detection for space division multiple access wireless systems

A symbol detector for wireless systems using space division multiple access (SDMA) and orthogonal frequency division multiplexing (OFDM) is derived. The detector uses a sphere decoder (SD) and has much less computational complexity than the naive maximum likelihood (ML) detector. We also show how to detect non-constant modulus signals with constrained least squares (CLS) receiver, which is designed for constant modulus (unitary) signals. The new detector outperforms existing suboptimal detectors for both uncoded and coded systems.     

回收草铵磷生产过程废溶剂的工艺设计及优化

针对草铵磷生产过程产生的废溶剂,设计了3种工艺流程用以回收其中的四氢呋喃、甲基亚磷酸二乙酯、亚磷酸三乙酯、混合三甲苯等有用组分. 分别对3种工艺路线进行实验计算,以产品的纯度、收率、能耗及设备造价为指标,考察分析确定最佳的工艺方案,为废溶剂的资源化再生利用提供可行方案.     

Visible Light Photocatalytic Properties and Thermochromic Phenomena of Nanostructured BiOCl Microspheres

Black nanostructured Bi OCl microspheres were directly synthesized by a hydrothermal method. The black balllike Bi OCl microspheres and black flower-like Bi OCl microspheres were obtained using different surfactant.The color of the Bi OCl microspheres turned from black to white when being annealed at 400℃ in air for 3 h and could be recovered to black by exposure to ultraviolet light for a few hours. The photocatalytic activity of both the black and the white Bi OCl microspheres was characterized by the photo-degradation of methyl orange dye under visible light irradiation. The black ball-like nanostructure Bi OCl displayed the best photocatalytic activity, compared with the white Bi OCl and the black flower-like Bi OCl. It can degrade the methyl orange dye to 20% within 70 min under visible light irradiation. The high activity of the Bi OCl ball-like sphere may own to its special morphology, strong absorption in visible light range and the existence of oxygen vacancies.     

Sequential Evaporation of Bi-Te Thin Films with Controllable Composition and Their Thermoelectric Transport Properties

We report a simplified sequential evaporation route that can deposit compositionally controllable Bi-Te thermoelectric (TE) thin films without the need for a highly controlled facility. Te and Bi granules were used as starting materials, with their ratio being adjusted to obtain Bi-Te films with different compositions and thicknesses. The as-evaporated and annealed films were subjected to structural and morphological analysis, and their transport properties were measured. X-Ray diffraction data revealed multiple phases for most films. Energy-dispersive x-ray spectroscopy showed that the film composition was Te-enriched due to the large vapor pressure difference of Te and Bi. A Bi₂Te₃ single phase was obtained in the annealed films, having nominal composition of BiTe_1.2. The existence of impurity phases, such as Bi₄Te₃ or elemental Te, was found in all the as-evaporated films and in the annealed films with other nominal Te/Bi ratios, which degraded the TE properties of the films by increasing their electrical conductivity and reducing their Seebeck coefficient. A pure Bi₂Te₃ film with nominal Te/Bi ratio of 1.2 exhibited a maximum power factor of 7.9 × 10^?4 W m^?1 K² after annealing at 200°C. This work demonstrated a simple, undemanding, reliable method to deposit Bi-Te-based TE thin films that can be utilized to fabricate low-cost TE microgenerators.     

Optimal beamforming for two-way multi-antenna relay channel with analogue network coding

This paper studies the wireless two-way relay channel (TWRC), where two source nodes, S1 and S2, exchange information through an assisting relay node, R. It is assumed that R receives the sum signal from S1 and S2 in one timeslot, and then amplifies and forwards the received signal to both S1 and S2 in the next time-slot. By applying the principle of analogue network coding (ANC), each of S1 and S2 cancels the so-called "self-interference" in the received signal from R and then decodes the desired message. Assuming that S1 and S2 are each equipped with a single antenna and R with multi-antennas, this paper analyzes the capacity region of the ANC-based TWRC with linear processing (beamforming) at R. The capacity region contains all the achievable bidirectional rate-pairs of S1 and S2 under the given transmit power constraints at S1, S2, and R. We present the optimal relay beamforming structure as well as an efficient algorithm to compute the optimal beamforming matrix based on convex optimization techniques. Low-complexity suboptimal relay beamforming schemes are also presented, and their achievable rates are compared against the capacity with the optimal scheme.     

基于深度学习的直肠癌放疗危及器官自动勾画的几何学和剂量学评估

基于几何学和剂量学指标评估基于深度学习的危及器官（Organs at risk, OARs）自动勾画的临床适用性,选取在复旦大学附属肿瘤医院接受放射治疗的35例直肠癌患者,采用自主开发的深度学习系统实现OARs自动勾画。以医生手动勾画的OARs作为参考,自动勾画的几何学评估指标包括戴斯相似系数（DSC）、雅卡尔相似系数（JSC）、豪斯多夫距离（HD）,平均一致性距离（MDA）。对于每个病例,基于自动勾画的OARs设计治疗计划,计划优化和评估过程与临床程序保持一致,记为Plan＿FD。比较Plan＿FD与原始临床治疗计划（记为Plan＿Treat）,以剂量体积参数和三维γ分析评估剂量学差异。自动勾画与手动勾画的OARs不仅在三维空间上高度重叠（DSC平均值大于0.85）,且在边缘细节上匹配度良好（MDA的平均值小于2.8 mm）。剂量学评估仅膀胱剂量（V30、V40、Dmean）有显著统计学差异（p<0.05）,其余OARs和靶区的剂量体积参数差异均无统计学意义。Plan＿FD与Plan＿Treat进行3 mm/3%标准的三维γ分析,γ≤1.0的点占比为（91.63±6.27）%。...     

A technical method to improve NOx/NH3 mixing ratio in SCR system and its engineering applications

A technical method for diagnosing the distribution of NO_x flux within the cross-section area in front of ammonia injection grid (AIG) was proposed for guiding the valve-tuning of AIG branch-pipes, in order to optimize the NO_x/NH₃ mixing ratio in the selective catalytic reduction (SCR) system of power plant. The weight coefficient of each branch-pipe in AIG system can be quantitatively determined with regard to the distribution of NO_x flux in the corresponding sub-zone of the cross-section area. The control strategy of the valves for different AIG branch-pipes can be achieved for guiding the NH₃ injection and improving the NO_x/NH₃ mixing ratio within the whole cross-section area in front of AIG. The technology has been applied on one side of the SCR system flue-gas tunnels (normally two tunnels for the SCR system called as A-side and B-side) of a 660 MW plant for more than one year. The ammonia consumption rate of the SCR system was reduced about 12.62% and the uniformity of outlet NO_x distribution was estimated to be greatly improved by about 79.01% with regard to the standard deviation. The rising rate of the flue gas resistance of the air preheater was slown down by 39.18% compared to that of the other flue-gas tunnel of SCR system. This implied that the formation of the sticky ammonium bisulfate (ABS) on air preheater was significantly inhibited through the application of this technology.     

尿素衍生产品的开发与应用

简要介绍了几种市场前景广阔的尿素深加工产品的开发及应用情况。