Case Retrieval Strategy of Turning Process Based on Grey Relational Analysis

To solve the problem of long response time when users obtain suitable cutting parameters through the Internet based platform,a case-based reasoning framework is proposed.Specifically,a Hamming distance and Euclidean distance combined method is designed to measure the similarity of case features which have both numeric and category properties.In addition,AHP(Analytic Hierarchy Process)and entropy weight method are integrated to provide features weight,where both user preferences and comprehensive impact of the index have been concerned.Grey relation analysis is used to obtain the similarity of a new problem and alternative cases.Finally,a platform is also developed on Visual Studio 2015,and a case study is demonstrated to verify the practicality and efficiency of the proposed method.This method can obtain cutting parameters which is suitable without iterative calculation.Compared with the traditional PSO(Particle swarm optimization algorithm)and GA(Genetic algorithm),it can obtain faster response speed.This method can provide ideas for selecting processing parameters in industrial production.While guaranteeing the characteristic information is similar,this approach can select processing parameters which is the most appropriate for the production process and a lot of time can be saved.

Analysis on the turning point of dynamic in-plane compressive strength for a plain weave composite

Experimental investigations on dynamic in-plane compressive behavior of a plain weave composite were performed using the split Hopkinson pressure bar. A quantitative criterion for calculating the constant strain rate of composites was established. Then the upper limit of strain rate, restricted by stress equilibrium and constant loading rate, was rationally estimated and confirmed by tests. Within the achievable range of 0.001/s-895/s, it was found that the strength increased first and subsequently decreased as the strain rate increased. This feature was also reflected by the turning point(579/s) of the bilinear model for strength prediction. The transition in failure mechanism, from local opening damage to completely splitting destruction, was mainly responsible for such strain rate effects. And three major failure modes were summarized under microscopic observations: fiber fracture, inter-fiber fracture, and interface delamination. Finally, by introducing a nonlinear damage variable, a simplified ZWT model was developed to characterize the dynamic mechanical response. Excellent agreement was shown between the experimental and simulated results.

COVID-19/Tuberculosis Co-Infection at the Epidemic Treatment Center (ETC) of Saint-Louis (Senegal): About 9 Cases

Introduction: COVID-19 is a global public health emergency that can cause acute respiratory distress syndrome. In countries where tuberculosis (TB) is endemic, coinfection of COVID-19 and TB is often encountered, which increases the risk of developing severe forms of COVID-19. Objectives: The aim of this study was to determine the prevalence of COVID-19/TB coinfection at the Epidemic treatment center (ETC) in Saint-Louis (Senegal) and to describe the epidemiological, clinical, paraclinical, and outcome profile of co-infected patients. Patients and Methods: This is a retrospective, cross-sectional, descriptive cohort study based on the records of COVID-19/ TB co-infected patients who were hospitalized at the ETC in Saint-Louis (Senegal) over an 18-month period from March 2020 to September 2021. Results: Out of a total of 454 hospitalizations, we collected records of 9 patients co-infected with COVID-19/TB, resulting in a prevalence of 2%. The study included patients with a median age of 34 years (range: 10-86 years), with a male predominance (7 cases) and a sex ratio of 3.5. The majority of patients (88.9%) had severe forms of COVID-19. Dyspnea and cough were reported in all patients (100%). Pulmonary TB was the most frequent localization, with 9 cases. The diagnosis of COVID-19 was confirmed by nasopharyngeal PCR in all patients (100%). Bacilloscopy was positive in 3 out of 5 cases. One patient tested positive for GeneXpert? MTB/RIF without rifampicin resistance. All patients were prescribed the hydroxychloroquine-azithromycin combination and anti-tuberculosis treatment. Out of the nine patients, four recovered (44.4%) and five died (55.5%). Conclusion: COVID-19/TB coinfection had a low prevalence in our cohort, but was associated with a high mortality due to the frequent occurrence of severe forms of the disease.

Profile of SARS-CoV-2 Infected Patients Hospitalized at the Epidemic Treatment Center (ETC) in Saint-Louis, Senegal during the First Two Waves

Introduction: The SARS-CoV-2 infection is a major public health emergency. Several risk factors are involved in the occurrence of respiratory distress that can lead to death despite resuscitation measures. Objectives: The aim of this study was to describe the epidemiological, clinical, paraclinical, therapeutic, and evolution profile of patients infected with SARS-CoV-2 hospitalized at the CTE of Saint-Louis (Senegal) during the first two waves. Patients and Methods: We conducted a retrospective, cross-sectional, descriptive, and analytical study that included all patients hospitalized at the ETC of Saint-Louis (Senegal) with SARS-CoV-2 infection from March 2020 to April 2021. Results: A total of 358 cases were collected, 256 (71.5%) during the first wave and 102 (28.5%) during the second wave. The mean age was 49.5 years (19.5). There was a male predominance (58.4%), with a sex ratio of 1.4. Hypertension was the main comorbidity, with 87 cases (24.3%). The most common functional signs were cough in 194 cases (54.2%), dyspnea in 143 cases (40%) and ageusia in 134 cases (37.4%). Thoracic CT scans were performed on 20 patients (5.6%), with severe involvement (50% - 75%) observed in 50% of cases. Hydroxychloroquine-azithromycin was prescribed to 351 patients (98%). Overall, 338 (94.4%) recovered and 17 (4.7%) died. In multivariate analysis, factors associated with death were male sex [OR = 2.645;95% CI: 1.530 - 4.785;p = 0.011], age 60 years [OR = 1.039;95% CI: 0.564 - 1.914;p = 0.002], the presence of comorbidities [OR = 2.171;95% CI: 0.564 - 3.429;p = 0.033], SpO2 (ambient air) 95% [OR = 2.061;95% CI: 0.616 - 3.827;p = 0.03], acute respiratory distress syndrome (ARDS) [OR = 0.635;95% CI: 0.316 - 1.275;p = 0.001], severe form [OR = 1.664;95% CI: 0.298 - 2.478;p = 0.016], occurrence of complications [OR = 0.521;95% CI: 0.287 - 0.944;p = 0.032], high creatinine levels [OR = 2.061;95% CI: 1.616 - 3.827;p = 0.026], and lymphopenia [OR = 0.485;95% CI: 0.370 - 0.636;p = 0.001]. Conclusion: In our series, infection with SARS-CoV-2 was associated with low lethality. Several risk factors were identified that need to be considered for successful management of patients.

TURNING LIGNIN INTO VALUABLE PRODUCTS

In a study published in Nature Catalysis on May 28,Chinese scientists unveiled a nove l approach to transforming lignin,a major component of woody biomass,into valuable chemical products(doi:10.1038/s41929-024-01165-w).This discovery could pave the way for more sustainable and efficient use of renewable resources.

Physiological Characterization of Green Turning of Rice Seedlings at Different Temperatures

Using early indica rice Zhongzao 39 and japonica rice Xiushui 134 as the experimental materials, the effects of 4 temperature levels after transplantation on turning green, leaf growth, tillering, dry matter accumulation and nutrition absorption were studied using a greenhouse and an artificial climate chest. We found that （1） tillering did not occur and growth of one new leaf took over 15 days at 16℃. New leaf growth took over 10 days and tillering occurred after 15 days of transplanta- tion at 19 ℃. Tillering appeared 10 days after planting and new leaf growth took 5 days between 22 and 25 ℃. This showed that low temperature impeded the turn- ing green of rice seedlings and the temperature must reach above 19 ℃ to ensure timely appearance of new leaf, tillering and turning green in rice seedlings. （2） When the temperature was 10 increased, both 100-seedling dry weight and nitrogen absorption increased. At temperatures lower 11 than 19 ℃, both dry weight incre- ment and nitrogen absorption were low. Nitrogen absorption of all organs increased obviously between 19 and 22 ℃. Thus, 19 ℃ was found to be an minimum tem- perature for plant organs to absorb nutrients. （3）Tiller of seedling cultivated on dry- land soil and substrate grew quickly and tillering occurred about 7 days after trans- planting. After that, the growth rate was about 0.18 tiller per day. For seedlings cultivated in slurry, tillering occurred 10 days after transplanting and the tillers grew at a rate of 0.16 tiller per day. However, substrate choice during the seedling rais- ing stage had no significant influence on leaf age. （4） Japonica rice exhibited stronger resistance to low temperature than indica rice. Tillering began at about the same time after transplanting in both rice varieties, but japonica rice exhibited higher tillering speed than early indica rice. The speed of leaf growth was higher in japoni- ca rice before transplantation but higher in indica rice after transplantation.

A Class of the Singularly Perturbed Boundary Value Problems for Elliptic Equation with a Super Surface of Turning Point in n-dimensional Space

In this paper, we study a class singular perturbed elliptic equation boundary value problem with a super surface of turning point in n-dimensional space by using the method of multiple scales and the comparison theorem. The uniformly valid asymptotic approxmations of solutions for the boundary value problem is constructed.

拟共形映射与Turning域

讨论了拟共形映射与Turning域及ILC域之间的关系.首先根据拟共形映射与Turning域的性质得到f是拟共形映射的充要条件是f将Rn中的Turning域映成Rn中的Turning域;然后根据Turning域及ILC域的等价性得到f是拟共形映射的充要条件是f将Rn中的ILC域映成Rn中的ILC域.

解读Louis Vuitton打造顶级品牌形象之谜

品牌形象是企业竞争力的核心。本文从树立品牌最为重要的部分--品牌形象入手,对国际顶级箱包品牌Louis Vuitton进行剖析,企图找到对民族企业有所启迪的东西。

3-Turns教学法在实践共同体促进深度学习中的应用

在电气工程专业实践教学过程中凝练出由Turn up、Turn away、Turn back等环节组成的3-Turns教学法。经过多轮的实践应用,3-Turns教学法在实践共同体中提供了一个兼具解释性与可操作性的教学样例。研究发现,3-Turns教学法对实践共同体促进工科生深度学习起到了提质增效的作用;3-Turns教学法为工程实践学习情境的强化设计提供了理论依据与经验支持。该研究验证了基于3-Turns教学法的实践共同体促进工科生深度学习的有效性,为助力工科人才培养质量的持续提升做出了积极的探索与实践。

Test of the Louis scheme and COARE algorithm for friction velocity in different wind-sea/swell regimes

The Louis scheme and the COARE algorithm （version 3.0） are tested against eddy covariance and inertial dissipation methods for friction velocity estimates in different wind-sea/swell regimes. Atmospheric forcing data, tabulated by Donelan et al. （1997.J Phys Oceanog, 27：2087-2099）, were collected from a mast on the foredeck of a SWATH （small water-plane area, twin hull） ship in deep sea off the State of Virginia during the surface wave dynamics experiment. These data are representative of low to moderate wind regimes. The aerodynamic roughness length is determined by using the Charnock relationship. The intercomparison shows that the Louis scheme and the COARE algorithm underestimate the friction velocity by 6% and 3% respectively under pure wind sea conditions, 15% and 13% respectively under cross swell conditions, and 21% and 17% respectively under counter swell conditions. The analysis shows that these underestimations were caused by the method chosen to determine the aerodynamic roughness length because it significantly underestimates the aerodynamic roughness length. It is especially true under the cross swell and counter swell conditions.

SURFACE ROUGHNESS PREDICTION MODEL FOR ULTRAPRECISION TURNING ALUMINIUM ALLOY WITH A SINGLE CRYSTAL DIAMOND TOOL

A surface roughness model utilizing regression analysis method is developedfor predicting roughness of ultra-precision machined surface with a single crystal diamond tool. Theeffects of the main variables, such as cutting speed, feed, and depth of cut on surface roughnessare also analyzed in diamond turning aluminum alloy. In order to predict the optimum cuttingconditions during process planning. A lot of experimental results show that the model can predictthe surface roughness effectively under a certain cutting conditions.

Microstructure refinement and work hardening in a machined surface layer induced by turning Inconel 718 super alloy

The microstructural changes in the machined surface layer of Ni-based super alloys essentially determine the final performance of the structural components of aerospace engines in which these alloys are used.In this work,multiscale metallurgical observations using scanning electron microscopy,electron-backscatter diffraction microscopy,and transmission electron microscopy were conducted to quantitatively characterize the microstructure of the machined subsurface.Next,to elucidate the factors that affect the formation of the refinement microstructure,the distributions of the deformation parameters(strain,strain rate,and temperature) in the machined subsurface were analyzed.A dislocation–twin interaction dynamic recrystallization mechanism for grain refinement during machining of Inconel 718 is proposed.Furthermore,microhardness evolution induced by grain refinement in the machined surface is evaluated.The results suggest that the gradient microstructure and the work hardening can be optimized by controlling the cutting parameters during turning of Inconel 718.

Investigations on spectroscopic parameters, vibrational levels, classical turning points and inertial rotation and centrifugal distortion constants for the 1 ＋ X^1∑g^＋ state of sodium dimer

The density functional theory （B3LYP, B3P86） and the quadratic configuration-interaction method including single and double substitutions （QCISD（T）, QCISD） presented in Gaussian03 program package are employed to calculate the equilibrium internuclear distance Re, the dissociation energy De and the harmonic frequency We for the XIEg＋ state of sodium dimer in a number of basis sets. The conclusion is gained that the best Re, De and We results can be attained at the QCISD/6-311G（3df,3pd） level of theory. The potential energy curve at this level of theory for this state is obtained over a wide internuclear separation range from 0.16 to 2.0 nm and is fitted to the analytic Murrell-Sorbie function. The spectroscopic parameters De, DO, Re, ωe, ωe Xe, αe and Be are calculated to be 0.7219 eV, 0.7135 eV, 0.31813 nm, 151.63 cm^-1, 0.7288 cm^-1, 0.000729 cm^-1 and 0.1449 cm^-1, respectively, which are in good agreement with the measurements. With the potential obtained at the QCISD/6-311G（3df,3pd） level of theory, a total of 63 vibrational states is found when J = 0 by solving the radial SchrSdinger equation of nuclear motion. The vibrational level, corresponding classical turning point and inertial rotation constant are computed for each vibrational state. The centrifugal distortion constants （Dr Hv, Lv, Mv, Nv and Ov） are reported for the first time for the first 31 vibrational states when J = 0.

Experimental Study on Hard Turning Hardened GCr15 Steel with PCBN Tool

This paper discusses experimental results of turnin g experiments on GCr15 bearing steel hardened to 60～64 HRC. The objective was to d etermine the effect of the cutting parameters on cutting force, chip morphology and resultant workpiece surface quality, more specifically surface texture, micr ostructure alterations, changes in microhardness and residual stresses distribut ion. The changing rules of the main cutting force was shown in this paper which feature a increasing tendency with the improvement of the workpiece hardness wit hin the cutting parameter scope. The rule of cutting force changing with the wor kpiece hardness is accord to the traditional metal cutting theory. Stress value decrease with increasing cutting speed and workpiece hardness. The comparison of the machined surface roughness and harden layer depth of machined surface for d ifferent hardness is shown in Fig.1. The machined surface roughness is the worst when the workpiece hardness is around 50HRC. When the workpiece hardness is ove r 50HRC, the surface roughness value shows a descending tendency with the additi on hardness. The machined superficial harden layer depth shows an increasing ten dency with the improvement of the workpiece hardness. When the workpiece hardnes s is 50HRC the machined superficial harden layer depth is tiptop. When the workp iece hardness is over 50HRC the depth changes little with the addition of workpi ece hardness. The remnant stress status of the machined surface is shown in Fig. 2, which is press stress status both in surface and in base for less cutting par ameters under two kinds of cutting condition. But experiment results show that t ensile stress can be produced under uncomfortable cutting conditions. The deform ation created by the chip formation is reduced whereduce with [TPP126A,+35mm77mm,Z,PY#]Depth from surface (μm) ■ v=200m/min,f=0.24mm/r,ap=0.8mm,60HRC ● v=200m/min,f=0.15mm/r,ap=0.5mm,60HRC Fig.1 The subsurface residual stress between the two experimentsHardness (HRC) Fig.2 The surface finish vs. workpiece hardness the workpiece hardness is improved.

A Statistical Model for Investigating Climatic Trend Turning Points

A two-phase trend model is presented to investigate the turning-point signals of evolution trend in long-term series of a climatic element. Based on nonlinear fitting, the revised model brings out more evident improvement of the linear model proposed by Solow et al. (1987). Both theoretical deduction and case calculation show that our version can search the turning point and period accurately and objectively. In particular it is fit for computer exploring the turning points in long-range records from stations covering a large area, thus avoiding subjective judgement by a usual drawing method.

Enhancement of surface wettability via micro-and nanostructures by single point diamond turning

Studies on surface wettability have received tremendous interest due to their potential applications in research and industrial processes. One of the strategies to tune surface wettability is modifying surface topography at micro-and nanoscales. In this research, periodic micro-and nanostructures were patterned on several polymer surfaces by ultra-precision single point diamond turning to investigate the relationships between surface topographies at the micro-and nanoscales and their surface wettability. This research revealed that single-point diamond turning could be used to enhance the wettability of a variety of polymers, including polyvinyl chloride(PVC), polyethylene 1000(PE1000), polypropylene copolymer(PP) and polytetrafluoroethylene(PFTE), which cannot be processed by conventional semiconductor-based manufacturing processes. Materials exhibiting common wettability properties(θ≈ 90°) changed to exhibit "superhydrophobic" behavior(θ > 150°). Compared with the size of the structures, the aspect ratio of the void space between micro-and nanostructures has a strong impact on surface wettability.

Cutting Temperature and Tool Wear of Hard Turning Hardened Bearing Steel

A study was undertaken to investigate the performan ce of PCBN tool in the finish turning GCr15 bearing steel with different hardness between 30～64 HRC. The natural thermocouple was used to measure the cutting tem p erature, tool life and cutting temperature were investigated and compared. The m aterial can be heated by this instrument which using low voltage and high elec trical current, while PCBN can’t be heated by electrifying directly, so the ke ntanium layer coating over the PCBN is heated, so the PCBN is heated and its th ermoelectric property is got by this method. [TPP129,+60mm88mm,Y,PZ#] Fig.1 Effect of cutting depth and workpiec hardness on. the cutting temperatureThe objective was to determine the influence of the workpiece hardness on change s in cutting temperature and tool wear characterize. It can be found from Fig.1 that the cutting temperature show an increasing tendency with the improvement of workpiece hardness within the cutting speed scope when the workpiece hardness i s under HRC50. And on the other hand, it is found that the cutting temperature s how the downtrend with the improvement of workpiece hardness when the workpiece hardness is over HRC50. According to experimental results, the critical hard ness when turning hardened GCr15 bearing steel with PCBN tool is about HRC50. Th e wear causes of PCBN tool have been found out through taking photos on the micr o-shape of PCBN poly-laminate initial surface as well as face and flank of wea r tool and analysis on chemical elements. It is discovered that the PCBN tools a re not suitable for cutting the workpiece at nearly critical hardness, because n ear the critical hardness, PCBN wear at the highest speed. For researching the w ear rule of PCBN tool, the tool wear experiments have been carried on by using b earing steel GCr15 at hardness HRC40 and HRC60 with changing cutting speed. The indexes of tool life equations is gained under two kinds of conditions w hich are bigger than 0.6, so the effects of cutting speed on the PCBN tool are m uch less than that of carbide tool and ceramic tool.

Clock-turning gait synthesis for humanoid robots

Turning gait is a basic motion for humanoid robots. This paper presents a method for humanoid tuming, i.e. clock-turning. The objective of clock-turning is to change robot direction at a stationary spot. The clock-turning planning consists of four steps： ankle trajectory generation, hip trajectory generation, knee trajectory generation, and inverse kinematics calculation. Our proposed method is based on a typical humanoid structure with 12 DOFs （degrees of freedom）. The final output of clock-turning planning is 12 reference trajectories, which are used to control a humanoid robot with 12 DOFs. ZMP （zero moment point） is used as stability criterion for the planning. Simulation experiments are conducted to verify the effectiveness of our proposed clock-turuing method.

Prediction of diameter errors compensation in bars turning

On the basis of analyzing the machine-workpiece-tool system, the main factors affecting diameter errors in bars turning are considered, and the mathematic models of the actual workpiece diameter at the cutting point are established according to the three usual methods of mounting workpieces on a turning machine. Further a prediction system for diameter errors is developed; a new method, called discrete nodes output, is presented and applied to expressing workpiece diameter errors at given points along the part axis, then off-line compensation is implemented according to the prediction values to diminish machining errors. The results indicate that the method can diminish diameter errors more than 70%, greatly improve the machining accuracy of bars.