Energy beam-based direct and assisted polishing techniques for diamond:A review

Diamond is a highly valuable material with diverse industrial applications,particularly in the fields of semiconductor,optics,and high-power electronics.However,its high hardness and chemical stability make it difficult to realize high-efficiency and ultra-low damage machining of diamond.To address these challenges,several polishing methods have been developed for both single crystal diamond(SCD)and polycrystalline diamond(PCD),including mechanical,chemical,laser,and ion beam processing methods.In this review,the characteristics and application scope of various polishing technologies for SCD and PCD are highlighted.Specifically,various energy beam-based direct and assisted polishing technologies,such as laser polishing,ion beam polishing,plasma-assisted polishing,and laser-assisted polishing,are summarized.The current research progress,material removal mechanism,and infuencing factors of each polishing technology are analyzed.Although some of these methods can achieve high material removal rates or reduce surface roughness,no single method can meet all the requirements.Finally,the future development prospects and application directions of different polishing technologies are presented.

Dual-salt poly(tetrahydrofuran) electrolyte enables quasi-solid-state lithium metal batteries to operate at -30 ℃

The stable operation of solid-state lithium metal batteries at low temperatures is plagued by severe restrictions from inferior electrolyte-electrode interface compatibility and increased energy barrier for Li^(+)migration.Herein,we prepare a dual-salt poly(tetrahydrofuran)-based electrolyte consisting of lithium hexafluorophosphate and lithium difluoro(oxalato)borate(LiDFOB).The Li-salt anions(DFOB−)not only accelerate the ring-opening polymerization of tetrahydrofuran,but also promote the formation of highly ion-conductive and sustainable interphases on Li metal anodes without sacrificing the Li^(+)conductivity of electrolytes,which is favorable for Li^(+)transport kinetics at low temperatures.Applications of this polymer electrolyte in Li||LiFePO_(4)cells show 82.3%capacity retention over 1000 cycles at 30℃and endow stable discharge capacity at−30℃.Remarkably,the Li||LiFePO4 cells retain 52%of their room-temperature capacity at−20℃and 0.1 C.This rational design of dual-salt polymer-based electrolytes may provide a new perspective for the stable operation of quasi-solid-state batteries at low temperatures.

基于双阶段元学习的小样本中医舌色域自适应分类方法

舌色是中医(TCM)望诊最关注的诊察特征之一。在实际应用中,通过一台设备采集到的舌象数据训练得到的舌色分类模型应用于另一台设备时,由于舌象数据分布特性不一致,分类性能往往急剧下降。为此,该文提出一种基于双阶段元学习的小样本中医舌色域自适应分类方法。首先,设计了一种双阶段元学习训练策略,从源域有标注样本中提取域不变特征,并利用目标域的少量有标注数据对网络模型进行微调,使得模型可以快速适应目标域的新样本特性,提高舌色分类模型的泛化能力并克服过拟合。接下来,提出了一种渐进高质量伪标签生成方法,利用训练好的模型对目标域的未标注样本进行预测,从中挑选出置信度高的预测结果作为伪标签,逐步生成高质量的伪标签。最后,利用这些高质量的伪标签,结合目标域的有标注数据对模型进行训练,得到舌色分类模型。考虑到伪标签中含有噪声问题,采用了对比正则化函数,可以有效抑制噪声样本在训练过程中产生的负面影响,提升目标域舌色分类准确率。在两个自建中医舌色分类数据集上的实验结果表明,在目标域仅提供20张有标注样本的情况下,舌色分类准确率达到了91.3%,与目标域有监督的分类性能仅差2.05%。

Water Scarcity in Conakry, Guinea: Challenges and Proposed Strategies for a Way Forward

The capital of Guinea, Conakry, faces a notable difficulty due to a water shortage, which is worsened by the rapid increase in population and urban development. The Guinean Water Company (SEG) faces challenges in supplying water to the entire city due to its limited area of approximately 420 km2 and a population of 2 million. Moreover, the population growth rate is anticipated to increase dramatically, exacerbating the difficulty of fulfilling future water requirements. As a result, this study employs data from the Knoema website and the Institute of National Statistics of Guinea (INS) to examine the water production and distribution process by the SEG. The study examines the challenges related to water scarcity in Conakry and suggests strategies to assist the city in managing the present circumstances and planning for the future. The primary objective is to get a long-lasting water supply and uphold water quality to advance public health.

基于ResNet-TSM和BiGRU网络的移动视频感知质量评价模型

考虑到卡顿、质量切换、内容特征等因素对用户体验质量的影响都会直接体现在客户端的失真视频里,提出了一种客户端的移动视频感知质量评价模型。该模型无须对每种影响因素均进行表征和度量,而是基于深度特征提取+回归的思路,直接建立失真视频与平均意见分数之间的映射模型。首先,构建了ResNet-TSM网络结构,提取失真视频片段的深度时空特征;为了避免维度灾难,采用LargeVis算法对提取的深度特征进行降维,同时提升特征的表达与区分能力。然后,采用双向门控循环单元网络对视频的长时间依赖关系进行建模,得到各视频片段的打分,再利用时间平均池化方法将各片段分数进行聚合,得到整个视频的打分结果。在WaterlooSQoE-Ⅲ和LIVE-NFLX-Ⅱ数据集上的实验结果表明,提出的模型可以获得更高的预测精度。

基于持续学习的中医舌色苔色协同分类方法

中医(traditional Chinese medicine, TCM)舌诊客观化研究中需要分析的舌象特征很多,不同的舌象特征往往采用单独的方法进行分析,导致分析系统的整体实现复杂度大幅增加。为此,基于持续学习的思想,提出一种中医舌色苔色协同分类方法,该方法将舌色分类作为旧任务,将苔色分类作为新任务,充分利用2个任务的相似性和相关性,仅通过一个网络结构就同时实现舌色和苔色的准确分类。首先,设计一种基于全局-局部混合注意力机制(global local hybrid attention, GLHA)的双分支网络结构,将网络高层语义特征与低层特征相融合,提升特征的表达能力;然后,提出基于正则化和回放相结合的持续学习策略,使得该网络在学习新任务知识的同时有效防止对旧任务知识的遗忘。在2个自建的中医舌象特征分析数据集上的实验结果表明,提出的协同分类方法可以获得与单个任务相当的分类性能,同时可以将2个分类任务的整体复杂度降低一半左右。其中,舌色分类准确率分别达到93.92%和92.97%,精确率分别达到93.69%和92.87%,召回率分别达到93.96%和93.16%;苔色分类准确率分别达到90.17%和90.26%,精确率分别达到90.05%和90.17%,召回率分别达到90.24%和90.29%。

新疆乌恰县沙冬青群落物种组成分析

采用样地调查法,对新疆乌恰县沙冬青〔Ammopiptanthus mongolicus(Maxim.ex Kom.)S.H.Cheng〕群落的物种组成进行分析。结果表明:沙冬青群落共有植物23种,隶属于13科21属,其中,苋科(Amaranthaceae)种类最多,含4属5种;61.5%的科仅含1属1种。群落中植物生活型中半灌木的占比最高(26.1%);灌木、小灌木和多年生草本的占比次之,均为21.7%,一年生草本的占比最低(8.7%)。沙冬青的相对频度和重要值最高,分别为12.7%和26.3%,为群落的优势种。综上所述,新疆乌恰县沙冬青群落物种组成简单,这与该地区所面临的人为干扰以及严酷生境条件密切相关,建议加强保护现有沙冬青群落,并建立沙冬青种子库,通过迁地移栽和人工育苗扩大群落规模。

大型高拱坝嵌深对坝肩块体稳定性的影响分析

结合古学拱坝坝肩不同嵌深设计方案,利用刚体和有限元极限平衡法,对坝肩块体进行稳定性分析,研究了高拱坝嵌深变化对坝肩块体稳定性的影响规律。结果表明,拱坝嵌深的增加会产生块体体积、滑面面积减小和拱推力增加两种效应,分别增加和降低块体稳定性,因此坝肩块体抗滑稳定安全系数随嵌深增加呈现出持续增大、持续减小、先增后减、先减后增4类变化趋势。经比选,推荐古学拱坝采用左岸嵌深36.5m、右岸嵌深40.5m的中嵌深方案。

All-fluorinated electrolyte for non-flammable batteries with ultra-high specific capacity at 4.7 V

Li metal batteries(LMBs)with LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)(NMC811)cathodes could release a specific energy of>500 Wh kg^(-1) by increasing the charge voltage.However,high-nickel cathodes working at high voltages accelerate degradations in bulk and at interfaces,thus significantly degrading the cycling lifespan and decreasing the specific capacity.Here,we rationally design an all-fluorinated electrolyte with addictive tri(2,2,2-trifluoroethyl)borate(TFEB),based on 3,3,3-fluoroethylmethylcarbonate(FEMC)and fluoroethylene carbonate(FEC),which enables stable cycling of high nickel cathode(LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2),NMC811)under a cut-off voltage of 4.7 V in Li metal batteries.The electrolyte not only shows the fire-extinguishing properties,but also inhibits the transition metal dissolution,the gas production,side reactions on the cathode side.Therefore,the NMC811||Li cell demonstrates excellent performance by using limited Li and high-loading cathode,delivering a specific capacity>220 mA h g^(-1),an average Coulombic efficiency>99.6%and capacity retention>99.7%over 100 cycles.

焦化厂硫氢化钠的应用实践

介绍了NaHS的回收处理原理。提出了一种利用H_(2)S治理过程中产生的NaHS副产品代替蒸氨过程中投加的NaOH的方法,并通过生产运行加以验证。运行结果表明:投加NaHS溶液后,蒸氨出口废水中的氨氮含量、pH值等指标均符合控制要求,还可节约50%的NaOH用量,NaOH价格按市场价1650元/t计算,每年可节约成本138万元。

A new measurement method of crack propagation rate for brittle rock under THMC coupling condition

A new electrical method of conductive carbon-film(with waterproof and anticorrosion ability)was proposed to continuously measure crack propagation rate of brittle rock under THMC coupling condition.A self-designed coupling testing system was used to conduct THMC coupling fracture tests of the pre-cracked red sandstone specimens(where the temperature is only changed)by this new electrical method of conductive carbon-film.Calculation results obtained by the energy method coincide well with the test results.And the higher the temperature is,the earlier the crack is initiated and the larger the crack propagation rate and accelerated velocity are,which can prove the validity of the new electrical method.This new electrical method has advantages of continuously measuring crack propagation rate over the conventional electrical,optical and acoustic methods,and can provide important basis for safety assessment and cracking-arrest design of deep rock mass engineering.

Crack initiation rate of brittle rock under thermal-hydro-mechanical coupling condition

A calculation formula of thermal-hydro-mechanical(THM)coupling crack initiation rate for brittle rock was derived based on the energy conservation law.The self-designed THM coupling fracture test with conductive adhesive electrical measurement method was applied to measuring the THM coupling crack propagation rate of brittle rock continuously.Research results show that both calculation and test results of crack initiation rate increased with increase of the temperature and the hydraulic pressure.They are almost in good agreement,which can prove validity of the calculation formula of THM coupling crack initiation rate.

以综合实践能力培养为目标的土力学实验课程改革

结合土力学实验教学中存在的问题,以学生实践能力培养为目标,针对专业研究和行业领域关注的土力学问题开展实验教学改革。围绕提升课程设计性和综合性提出具有较强自主性、开放性和实践性的实验课题,学生以项目小组形式全过程负责研究背景、方案设计、实验准备、试验测试及结果分析等实践过程,激发学习主动性,提高实践和创新能力,具有较好的教学效果和示范意义。

Influences of top clearance and liquid throughput on the performances of an external loop airlift slurry reactor integrated mixing and separation

A new developed external loop airlift slurry reactor, which was integrated with gas–liquid–solid three-phase mixing, mass transfer, and liquid–solid separation simultaneously, was deemed to be a promising slurry reactor due to its prominent advantages such as achieving continuous separation of clear liquid from slurry and cyclic utilization of solid particles without any extra energy, energy-saving, and intrinsic safety design. The principal operating parameters, including gas separator volume, handling capacity, and superficial gas velocity, are systematically investigated here to promote the capabilities of mixing, mass transfer, and yield in the pilot external loop airlift slurry reactor. The influences of top clearance and throughput of the clear liquid on flow regime and gas holdup in the riser, liquid circulating velocity, and volumetric mass transfer coefficient with a typical high solid holdup and free of particles are examined experimentally. It was found that increasing the gas separator volume could promote the liquid circulating velocity by about 14.0% at most. Increasing the handling capacity of the clear liquid from 0.9 m3·h-1 to 3.0 m3·h-1 not only could increase the output without any adverse consequences, but also could enhance the liquid circulating velocity as much as 97.3%. Typical operating conditions investigated here can provide some necessary data and guidelines for this new external loop airlift slurry reactor to upgrade its performances.

Effect of Au/Ni/4H–SiC Schottky junction thermal stability on performance of alpha particle detection

Au/Ni/n-type 4H-SiC Schottky alpha particle detectors are fabricated and annealed at temperatures between 400℃ and 700 ℃ to investigate the effects of thermal stability of the Schottky contact on the structural and electrical properties of the detectors. At the annealing temperature of 500 ℃, the two nickel silicides （i.e., Ni31Sil2 and Ni2Si） are formed at the interface and result in the formation of an inhomogeneous Schottky barrier. By increasing the annealing temperature, the Ni31Sil2 transforms into the more stable Ni2Si. The structural evolution of the Schottky contact directly affects the electrical properties and alpha particle energy resolutions of the detectors. A better energy resolution of 2.60% is obtained for 5.48-MeV alpha particles with the detector after being annealed at 600 ℃. As a result, the Au/Ni/n-type 4H-SiC Schottky detector shows a good performance after thermal treatment at temperatures up to 700℃.

Thermo-hydro-mechanical-chemical(THMC)coupling fracture criterion of brittle rock

Based on analysis of thermo-hydro-mechanical-chemical(THMC)coupling mechanism for brittle rock,THMC coupling indicator in terms of rock porosity was introduced to represent the influencing degree of THMC coupling field on stress field in order to establish THMC coupling fracture criterion.A novel real-time measurement method of permeability(related to porosity)was proposed to determine the THMC coupling indicator,and self-designed THMC coupling tests and scanning electron microscope tests were conducted on pre-cracked red sandstone specimens to study the macroscopic and microscopic fracture mechanism.Research results show that the higher the hydraulic pressure is,the smaller the crack initiation load is and the easier the Mode I fracture occurs.Test results are in good agreement with prediction results(crack initiation load and angle,and fracture mode),which can verify the effectiveness of the newly established THMC coupling fracture criterion.This new fracture criterion can be also further extended to predict THMC coupling fracture of multi-crack problem.

Hyper-accuracy three-dimensional reconstruction as a tool for better planning of retroperitoneal liposarcoma resection: A case report

BACKGROUND Well-differentiated liposarcoma is the second most common pathologic type of retroperitoneal sarcoma.It is characterized by a huge mass,but multiple organ invasions are common.Surgery is the only treatment option for potential cure.Hyper-accuracy three-dimensional(3D)reconstruction is widely used in robotic partly nephrectomy owing to its ability to visualize overlapping anatomy.CASE SUMMARY A 54-year-old man was admitted for progressive abdominal distension over the preceding 2 mo.Computed tomography revealed a 32 cm×21 cm×12 cm lipomatous mass.Hyper-accuracy 3D reconstruction was performed because of the complex relationship between the mass and nearby tissue.The patient underwent surgical resection,and the tumor did not recur for over 16 mo.CONCLUSION Hyper-accuracy 3D reconstruction is useful for operative planning owing to its intuitiveness and precise determination of anatomical structures in both tumors and nearby tissues.

Study on the effect of Baiban Ointment on the whole gene expression profile of vulvar sclerosing lichen

Objective:To study the effect of Baiban Ointment on gene expression profile of vulvar lichen sclerosus before and after treatment,and to provide theoretical basis for the early diagnosis and clinical treatment of vulvar lichen sclerosus.Methods:Nine patients with vulvar lichen sclerosus diagnosed pathologically were selected as the study object,and the Baiban ointment was applied locally for 3 months.Gene chip technology was used to detect the vulva skin tissue in the same area before and after treatment,and the peripheral normal skin was used as the normal control group to analyze the change of gene expression profile.FC and P values were used as research indicators,and the standard of differential expression was FC value≥1.5,P value<0.05.The differentially expressed genes were screened,and GO analysis and KEGG database gene pathway analysis were carried out.Results:Compared with the normal control group,there were 22 differentially expressed genes in Group A before treatment,of which 21 were up-regulated and 1 was down regulated;compared with Group B before treatment,there were 23 differentially expressed genes,all of which were up regulated.The differentially expressed genes related to Baiban ointment treatment included TBK1、STAT1、ITGAM、VCAN、PRKACB、PROM1、PLAT、SERPINA1.Go analysis showed that the up-regulated differential genes were mainly concentrated in the extracellular exosome,cytosol,extracellular space,Golgi apparatus and other cellular component,using the biological process such as positive regulation of cell metabolism,signal transduction regulation,cell adhesion,etc.,to play a role in protein binding,enzyme activity regulation and other molecular functions.KEGG signaling pathway showed that the differentially expressed genes were significantly enriched in Toll like receptor signaling pathway,Nod like receptor signaling pathway and Fc RI signaling pathway,all of which were up-regulated signaling pathways.Among them,Toll like receptor signaling pathway and Nod like receptor signaling pathway are most closely related to the disease.Conclusion:Baiban ointment may play a role in regulating metabolism,inflammation and immune response by regulating the expression of related genes,affecting the signal transduction such as Toll like receptor signal pathway.The pathway and the genes screened in this study will provide a direction for the future study of this disease.

基于深度学习的单幅图像去雾研究进展

户外视觉系统极易受到雾霾等恶劣天气影响,采集到的图像/视频质量严重下降,这不仅影响人眼的主观感受,也给后续的智能化分析带来严峻挑战.近年来,学者们将深度学习应用于图像去雾领域,取得了诸多的研究成果.但是雾霾图像场景复杂多变、降质因素众多,这对去雾算法的泛化能力提出了很高的要求.本文主要总结了近年来基于深度学习的单幅图像去雾技术研究进展.从先验知识和物理模型、映射关系建模、数据样本、知识迁移学习等角度出发,介绍了现有算法的研究思路、具体特点、优势与不足.尤其侧重于近两年来新出现的训练策略和网络结构,如元学习、小样本学习、域自适应、Transformer等.另外,本文在公共数据集上对比了各种代表性去雾算法的主客观性能、模型复杂度等,尤其是分析了去雾后的图像对于后续目标检测任务的影响,更全面地评价了现有算法性能的优劣,并探讨了未来可能的研究方向.

Midline Prostatic Cysts Presenting with Chronic Prostatitis or Secondary Infertility and Minimally Invasive Treatment: Endoscopic or Laparoscopic Approach?

Backgrounds: Surgical interventions especially minimally invasive treatments are recommended for symptomatic midline prostatic cysts. The endoscopic unroofing of cysts close to urethra is easy and simple, but it has little effect on the large cysts and cysts lying deeply, in contrast with the laparoscopic approach. Therefore, the selection of minimally invasive therapeutic approaches is important. The aim of this study is to describe our experience in the diagnosis and selection of minimally invasive treatment for midline prostatic cyst. Methods: 15 cases of midline prostatic cyst were studied.10 cases presented with prostatitis-like symptoms, 1 with dysuria and acute urinary retention, 3 with secondary infertility and the rest 1 with hemospermia. 6 patients presented with small cysts (≤2 cm × 2 cm) close to urethra and underwent transurethral unroofing. The other 9 patients with large cysts (>2 cm × 2 cm) or cysts lying closely behind the prostate received the laparoscopic excision. Results: The average duration of transurethral unroofing and laparoscopic excision was 39 mins and 118 mins respectively, whereas the average time of hospitalization was 2.7 days and 4.5 days respectively. After a follow-up of 21 months, all cases were treated successfully without complications and recurrence. Their prostatitis-like symptoms disappeared, and the three patients presented with secondary infertility achieved conception within one year after the operation. Conclusions: A midline prostatic cyst can present with chronic prostatitis-like symptoms and secondary infertility. It can be cured by minimally invasive treatments, but these procedures should be carefully selected according to the size and location of the cyst.