Development of separation sharpness model for hydrocyclone

Hydrocyclones are mechanical devices used in classifying and separating many different types of materials.A classification function of the hydrocyclone has been continually developed for solid–liquid separation.In the classification process of solids from liquids,it is desirable to reduce the amount of misplaced material;therefore,the separation sharpness,α(alpha),is a parameter that helps in evaluating misplaced material and has been developed as a model to help the designer predict the performance of the classification.However,the problem with the separation sharpness model is that it cannot be used outside the range of conditions under which it was developed.Therefore,this research aimed to develop the separation sharpness model to predict more accurately and cover a wide range of conditions using the multiple linear regression method.The new regression model of separation sharpness was based on a wide range of both experimental and industrial data-sets of 431 tests collaborating with the additional experiments of 117 tests that were obtained from a total of 548 tests.The new model of separation sharpness can be used in the range of 30–762 mm hydrocyclone body diameters and feed solid concentrations in the range of 0.5 wt%–80 wt%.When compared with the experimental separation sharpness,the accuracy of the separation sharpness model prediction has an error of 4.53%and^of 0.973.

Sharpness of the paired 660-km discontinuity beneath the Izu-Bonin area

The 660-km discontinuity that separates the Earth's upper and lower mantle has primarily been attributed to phase changes in olivine and other minerals.Resolving the sharpness is essential for predicting the composition of the mantle and for understanding its dynamic effects.In this study,we used S-to-P conversions from the 660-km interface,termed S660P,arriving in the P-wave coda from one earthquake in the Izu–Bonin subduction zone recorded by stations in Alaska.The S660P signals were of high quality,providing us an unprecedented opportunity to resolve the sharpness of the discontinuity.Our study demonstrated,based on the impedance contrast given by the IASP91 model,that the discontinuity has a transitional thickness of^5 km.In addition,we observed a prominent arrival right after the S660P,which was best explained by S-to-P conversions from a deeper discontinuity at a depth of^720 km with a transitional thickness of^20 km,termed S720P.The 720-km discontinuity is most likely the result of a phase transition from majoritic garnet to perovskite in the segregated oceanic crust(mainly the mid-oceanic ridge basalt composition)at the uppermost lower mantle beneath this area.The inferred phase changes are also consistent with predictions from mineral physics experiments.

Technique for Measuring the Sharpness of Staple Fiber Cutter Blades

Quantitative measurement of the cutter blade sharpness is yet a difficult problem, since so far there has been no appropriate testing method. In this paper, a technique is introduced for measuring the cutter blade sharpness at different testing conditions. The sharpness of cutter blades are measured by detecting the force to cut off the fiber with a material strength testing machine, and the results indicated that the technique could be used to measure the cutter blade sharpness satisfactorily. The fiber tension and downward speed of cutter blades are recommended to be 4.9 cN and 50 mm/min respectively for cutting 0.22 mm PET fiber.

Tool sharpness in precision micro cutting process

As to probe the factors affecting the roughness and surface properties of work piece in mirco-cutting machining process, according to the principle of energy balance, using the method of experiments combining with theoretical analysis, this paper investigates the effect of cutting edge radius on the unit cutting force, the cutting component forces ratio Fy/Fz, as well as the roughness and surface properties of the work-piece. Experimental results show that the value of tool cutting edge arc ρ has a significant impact on elastic-plastic deformation of the cutting area, and its influence on the surface quality of processing and precision is greater than common cutting. The method of calculating the theoretical limits of the diamond tool cutting edge radius is feasible. The value of 0.0001 μm has some guiding significance for the developement of suitable cutting thickness to ensure the normal cutting.

肾内科教学中采用SHARP反馈法的效果及对教学满意度的影响

目的探析SHARP反馈法在肾内科教学中的应用效果。方法选取2021年5月至2022年5月皖南医学院弋矶山医院肾内科实习生50名,依据随机数表法分为两组,每组各25名。对照组采用传统教学方法,观察组采用SHARP反馈法。比较两组学习成绩、教学质量评分及教学满意度。结果观察组学生学习成绩、教学质量评分包括学习和学术价值、教师的情操、组织和表达、师生关系和互动、教师知识面评分高于对照组,差异有统计学意义(P<0.05),观察组教学满意度、学习能力评分包括学生临床思维、课堂氛围、自学能力、临床实践能力、表达能力及知识关联能力高于对照组,差异有统计学意义(P<0.05)。结论肾内科教学中采用SHARP反馈法教学的效果明显,可提升实习生学习成绩,为实习生提供高质量教学,同时提升实习生对教学方法的满意度,临床教学中可大力推广及应用。

Gloo+:利用在网计算技术加速分布式深度学习训练

在分布式深度学习训练中,聚合通信是主要的通信方式。在聚合通信优化的研究中,有软件层面的优化和硬件层面的优化。SHARP是Mellanox提出来的一种聚合通信网络卸载协议,是针对聚合通信在硬件上的优化,其将聚合操作卸载到网络中的交换机,进而缩短了聚合通信时间。在Gloo的基础上集成了SHARP技术,设计并实现了一个能够利用在网计算技术来加速分布式深度学习训练的聚合通信库——Gloo+。评估并比较了Gloo+、Gloo以及MPI中聚合操作的性能,并将Gloo+应用于分布式深度学习训练中,以此来检验其实战能力。对Gloo+的实验评估结果显示,在基准测试时,在消息大小较小的情况下,Gloo+相对于Gloo的加速比最高能达到100以上;相比于以太网模式下的MPI,其加速比最高也能达到50以上;相比于IB网模式下的MPI,其加速比在10以内。在分布式深度学习训练的实际应用中,Gloo+相比于Gloo加速比最高能达到1.1,相比于以太网模式下的MPI加速比最高有1.3,相比于IB网模式下的MPI加速比最高有0.5。

Sharpness of some properties of weighted modulation spaces

We obtain some optimal properties on weighted modulation spaces. We find the necessary and sufficient conditions for product inequalities, convolution inequalities and embedding on weighted modulation spaces. Especially, we establish the analogue of the sharp Sobolev embedding theorem on weighted modulation spaces.

向量值多线性奇异积分算子的加权Sharp不等式

利用不等式、原子分解性质研究了向量值多线性算子,证明了某些向量值多线性奇异积分算子的一个加权Sharp不等式,并利用此不等式得到了该向量值多线性算子的加权L^(p)型不等式和L log L型不等式。

On the tip sharpness of riblets for turbulent drag reduction

It is commonly known that riblets with sharper tip generally have better turbulent drag reduction capacity,which,however,poses great challenges for manufacturing and makes the riblets vulnerable to tip erosion.In this study,we show that a scalloped riblet which is not as sharp in the tip as corresponding triangular riblet with same height-width ratio,nevertheless has a larger protrusion height,a quantity solely depending on the riblet shape and calculated through a boundary element algorithm in this study,and thus a higher projected drag reduction rate.In addition,it is found that,when subjected to tip rounding,this scalloped riblet performs better in terms of protrusion height than corresponding parabolic riblet,which indicates stronger resilience to riblet tip erosion.With the class of scalloped riblets,designed by smoothly connecting two third-order polynomials and thus the tip sharpness and valley curvature can be well defined,it is revealed that two mechanisms,one for the valley curvature at the viscous limit and one for the tip sharpness at infinite deep limit,determine the protrusion height,and thus the projected drag reduction capacity.Direct numerical simulations are then carried out to investigate controlled boundary layer transition with the scalloped riblet of width s+=20 and 5+=60.A 7.8%drag reduction in the turbulent region is found for the smaller riblet with a preferable transition delay,while for the larger riblet transition is promoted and drag is increased in the turbulent region.It is also found that the area fraction of high drag region around the riblet tips is basically the same for the two cases.Surprisingly,even higher drag is found around the tip region for the smaller drag-reducing riblets.On the other hand,a much smaller drag coefficient is found in the valley of the smaller riblet,which results in the reduction of turbulent drag.It is thus inferred that the issue of sharp riblet tip,that hard to manufacture and deteriorate substantially when subjected to tip erosion,could be mitigated by optimization of the riblet geometry.

Variational reconstruction using subdivision surfaces with continuous sharpness control

We present a variational method for subdivision surface reconstruction from a noisy dense mesh. A new set of subdivision rules with continuous sharpness control is introduced into Loop subdivision for better modeling subdivision surface features such as semi-sharp creases, creases, and corners. The key idea is to assign a sharpness value to each edge of the control mesh to continuously control the surface features.Based on the new subdivision rules, a variational model with L_1 norm is formulated to find the control mesh and the corresponding sharpness values of the subdivision surface that best fits the input mesh. An iterative solver based on the augmented Lagrangian method and particle swarm optimization is used to solve the resulting non-linear, non-differentiable optimization problem. Our experimental results show that our method can handle meshes well with sharp/semi-sharp features and noise.

Innovations Not Enough—Yet—to Make Headset Market an Actual Reality

In January 2024,after decades of intermittent improvements in virtual reality(VR)and augmented reality(AR)devices failing to help the technology catch on with the public,tech behemoth Apple(Cupertino,CA,USA)launched its marketing of a headset with by far the highest resolution and sharpest contrast of any commercially available device to date[1].Yet sales of the Vision Pro(Fig.1),Apple’s much anticipated first entry in the VR/AR marketplace,have fallen far short of the company’s already low expectations[2].

The Paris 2024 Olympic and Paralympic Games

The first modern Olympic Games took place in Athens in 1896.While in those early days of the Olympics only amateur and gentleman athletes were allowed to participate,today Olympic athletes are highly trained professionals often dedicating decades of preparation for the chance to compete in the Olympic Games.In sharp contrast to these highly trained athletes,the world’s population becomes less physically active on average,resulting in an obesity epidemic with associated metabolic syndrome and increased mortality through non-communicable diseases(e.g.,Collins et al.^(1)).

STABILITY OF THE RAREFACTION WAVE IN THE SINGULAR LIMIT OF A SHARP INTERFACE PROBLEM FOR THE COMPRESSIBLE NAVIER-STOKES/ALLEN-CAHN SYSTEM

This paper is concerned with the global well-posedness of the solution to the compressible Navier-Stokes/Allen-Cahn system and its sharp interface limit in one-dimensional space.For the perturbations with small energy but possibly large oscillations of rarefaction wave solutions near phase separation,and where the strength of the initial phase field could be arbitrarily large,we prove that the solution of the Cauchy problem exists for all time,and converges to the centered rarefaction wave solution of the corresponding standard two-phase Euler equation as the viscosity and the thickness of the interface tend to zero.The proof is mainly based on a scaling argument and a basic energy method.

六盘水市水上交通安全气象保障服务系统的开发应用

为了降低气象灾害对六盘水市水上交通安全的影响,本文研发并应用了六盘水水上交通安全气象保障服务系统。该系统通过自动气象站收集实时数据,利用C Sharp Program编程语言和一体化平台设计实现数据处理、监测预报预警以及服务产品的生成与分发。系统针对主要航道过去24小时天气、未来24小时天气预报和大风气象风险进行预警提示,有效提高了航运安全和气象服务质量。尽管存在监测范围有限、数据时效性、灾害风险评估不全面等问题,但通过增加监测点、提高数据更新频率、扩展风险评估模型等优化措施,系统性能将得到进一步提升。该系统的应用降低了安全风险,扩大了气象服务影响,提升了气象服务能力,为地方政府、海事局提供了有力的现代化航运气象保障服务。未来工作将侧重于系统的持续完善,以满足更广泛的业务需求。

Management of Penetrating Cranioencephalic Trauma Caused by Sharp Metal Objects—Therapeutic and Evolutionary Aspects: 12 Cases at the Renaissance University Hospital in N’Djamena

Introduction: Cranioencephalic trauma caused by bladed weapons is rare, and that caused by sharp objects is exceptional. The aim of our study was to describe the clinical, therapeutic and evolutionary aspects. Materials and method: This was a descriptive and analytical study over a 48-month period at CHU la Renaissance from January 1, 2018 to December 31, 2021, concerning patients admitted for penetrating cranioencephalic trauma by pointed object. Results: Twelve cases, all male, of penetrating cranioencephalic sharp-force trauma were identified. The mean age was 34 ± 7 years, with extremes of 11 and 60 years. Farmers and herders accounted for 31% and 25% of cases respectively. The average admission time was 47 hours. Brawls were the circumstances of occurrence in 81.2% of cases. Knives (33%), arrows (25%) and iron bars (16.6%) were the objects used. Altered consciousness was present in 43.8% of cases, and focal deficit in 50%. Scannographic lesions were fracture and/or embarrhment (12 cases), intra-parenchymal haematomas (6 cases) and presence of object in place (4 cases). Surgery was performed in 11 patients. Postoperative outcome was favorable in 9 patients. After 12 months, 2 patients were declared unfit. Conclusion: Penetrating head injuries caused by sharp objects are common in Chad. Urgent surgery can prevent disabling after-effects.

Cost-Efficient Medium Frequency Propagation Research with Software Defined Radio

Medium Frequency radio holds significance in modern society as it supports broadcasting and individual communications in the public, government, and military sectors. Enhancing the availability and quality of these communications is only possible by enhancing the understanding of medium frequency propagation. While traditional methods of radio wave propagation research can have a high material demand and cost, software defined radio presents itself as a versatile and low-cost platform for medium frequency signal reception and data acquisition. This paper details a research effort that utilizes software defined radio to help characterize medium frequency signal strength in relation to ionospheric and solar weather propagation determinants. Signal strength data from seven medium frequency stations of unique transmission locations and varying transmission powers were retrieved in 24-hour segments via a receiving loop antenna, Airspy HF+ Discovery software defined radio, and SDR Sharp software interface network. Retrieved data sets were visualized and analyzed in MATLAB for the identification of signal strength trends, which were subsequently compared to historical ionospheric and space weather indices in pursuit of a quantifiable correlation between such indices and medium frequency signal strengths. The results of the investigation prove that software defined radio, when used in conjunction with a receiving antenna and data analysis program, provides a versatile mechanism for cost-efficient propagation research.

一款学习型游戏设计与制作

以音视频系统为例,设计制作出一款基于音视频系统的学习型卡牌游戏,游戏将Unity 3D游戏引擎作为开发工具,C sharp作为开发语言。游戏中使用了UGUI绘制主菜单及相关界面,以不同Button按钮实现不同界面和不同场景之间的切换,编辑不同动画及音效,为玩家营造一种欢快、轻松的游戏环境。通过卡牌游戏学习知识,相较于一般单纯的课本学习,能够有效提高人们的学习效率,增强学习热情和主动性。

复合保温一体板施工质量控制技术研究

随着传统保温板脱落情况频繁发生,新材料复合保温一体板大量投入使用。由于该工艺技术及其规范的不足,在施工过程中其施工质量存在明显缺陷。本文将采用CAD和sharp3D软件对于工人实操过程进行交底讲解,有效降低安装出错率;通过垫片加固方式有限减少阴阳角拼接处倾斜和漏浆等现象。该控制技术的使用极大降低了返工和返修率,提高了该项目的经济效益。

输电线路塔基断面图与数据表的自动化输出研究与应用

通过分析架空输电线路测量中塔基断面图绘制和塔基数据表输出的需求,利用C#语言开发、设计了对塔基测量点数据自动处理与输出的软件,实现了基于AutoCAD二次开发的塔基断面图自动绘制和基于Excel格式的塔基数据表自动输出。通过工程实践证明,该软件自动化程度高、精度可靠,极大地减轻了内业数据处理的工作量,具有较好的工程应用价值。

Numerical Study of a Three-Dimensional Laminar Flow in a Rectangular Channel with a 180-Degree Sharp Turn

This study presents a numerical analysis of three-dimensional steady laminar flow in a rectangular channel with a 180-degree sharp turn. The Navier-Stokes equations are solved by using finite difference method for Re = 900. Three-dimensional streamlines and limiting streamlines on wall surface are used to analyze the three-dimensional flow characteristics. Topological theory is applied to limiting streamlines on inner walls of the channel and two-dimensional streamlines at several cross sections. It is also shown that the flow impinges on the end wall of turn and the secondary flow is induced by the curvature in the sharp turn.