Experimental research and energy analysis of a new type of dry ice powder pneumatic rock breaking technology

When the traditional drill and blast method is applied to rock crushing projects,it has strong vibration,loud noise and dust pollution,so it cannot be used in densely populated areas such as urban public works.We developed a supercritical CO_(2)true triaxial pneumatic rock-breaking experimental system,and conducted laboratory and field tests of dry ice powder pneumatic rock-breaking.The characteristics of the blast-induced vibration velocity waveform and the evolution of the vibration velocity and frequency with the focal distance were analyzed and discussed.The fracturing mechanism of dry ice powder pneumatic rock breaking is studied.The research results show that:(1)The vibration velocity induced by dry ice powder pneumatic rock breaking decays as a power function with the increase of the focal distance;(2)The vibration frequency caused by dry ice powder pneumatic rock breaking is mainly distributed in 1–120 Hz.Due to the dispersion effect,the dominant frequency of 10–30 Hz appears abnormally attenuated;(3)The traditional CO_(2)phase change fracturing energy calculation formula is also applicable to dry ice pneumatic rock breaking technology,and the trinitrotoluene(TNT)equivalent of fracturing energy is applicable to the Sadovsky formula;(4)Dry ice powder pneumatic rock breaking is shock wave and highenergy gas acting together to fracture rock,which can be divided into three stages,among which the gas wedge action of high-energy gas plays a dominant role in rock mass damage.

Integrated transcriptome and proteome analysis provides insight into chilling-induced dormancy breaking in Chimonanthus praecox

Chilling has a critical role in the growth and development of perennial plants.The chilling requirement(CR)for dormancy breaking largely depends on the species.However,global warming is expected to negatively affect chilling accumulation and dormancy release in a wide range of perennial plants.Here,we used Chimonanthus praecox as a model to investigate the CR for dormancy breaking under natural and artificial conditions.We determined the minimum CR(570 chill units,CU)needed for chilling-induced dormancy breaking and analyzed the transcriptomes and proteomes of flowering and non-flowering flower buds(FBs,anther and ovary differentiation completed)with different CRs.The concentrations of ABA and GA3 in the FBs were also determined using HPLC.The results indicate that chilling induced an upregulation of ABA levels and significant downregulation of SHORT VEGETATIVE PHASE(SVP)and FLOWERING LOCUS T(FT)homologs at the transcript level in FBs when the accumulated CR reached 570 CU(IB570)compared to FBs in November(FB.Nov,CK)and nF16(non-flowering FBs after treatment at 16℃for−300 CU),which suggested that dormancy breaking of FBs could be regulated by the ABA-mediated SVP-FT module.Overexpression in Arabidopsis was used to confirm the function of candidate genes,and early flowering was induced in 35S::CpFT1 transgenic lines.Our data provide insight into the minimum CR(570 CU)needed for chilling-induced dormancy breaking and its underlying regulatory mechanism in C.praecox,which provides a new tool for the artificial regulation of flowering time and a rich gene resource for controlling chilling-induced blooming.

Failure analysis of polycrystalline diamond compact cutters for breaking rock by bending waves theory

The breakage mechanism of the polycrystalline diamond compact(PDC) cutters was analyzed by the energy theory of bending waves. The cutting tests of granite block were conducted on a multifunctional testing device by using the cutter at three kinds of negative fore angles of 30°, 45° and 60°. The results show that, when the edge of the PDC layer is broken, the layer of tungsten cobalt is broken a little under the angle of 30°, while the layer of tungsten cobalt is broken continuously under the angle of 60°, their maximum depths are about 2 and 7 mm respectively in the two cases. The eccentric distance mainly depends on the negative fore angle of the cutter. When the cutter thrusts into the rock under an attack angle of 60°, the energy of bending waves reaches the maximum since the eccentric distance is the maximum. So the damage of cutter is the most serious. This test result is consistent with the conclusion of theoretical analysis well. The eccentric distance from the axial line of cutter to the point of action between the rock and cutter has great effect on the breakage of the cutter. Thus during the process of cutting, the eccentric distance should be reduced to improve the service life of PDC cutters.

Numerical analysis on coal-breaking process under high pressure water jet

Based on the theory of nonlinear dynamic finite element,the control equation ofcoal and water jet was acquired in the coal breaking process under a water jet.The calculationmodel of coal breaking under a water jet was established;the fluid-structure couplingof water jet and coal was implemented by penalty function and convection calculation.The dynamic process of coal breaking under a water jet was simulated and analyzed bycombining the united fracture criteria of the maximum tensile strain and the maximal shearstrain in the two cases of damage to coal and damage failure to coal.

Analysis of the Flow Field Characteristics Associated with the Dynamic Rock Breaking Process Induced by a Multi-Hole Combined External Rotary Bit

The characteristics of the flow field associated with a multi-hole combined external rotary bit have been studied by means of numerical simulation in the framework of an RNG k-εturbulence model,and compared with the results of dedicated rock breaking drilling experiments.The numerical results show that the nozzle velocity and dynamic pressure of the nozzle decrease with an increase in the jet distance,and the axial velocity of the nozzle decays regularly with an increase in the dimensionless jet distance.Moreover,the axial velocity related to the nozzle with inclination angle 20°and 30°can produce a higher hole depth,while the radial velocity of the nozzle with 60°inclination can enlarge the hole diameter.The outcomes of the CFD simulations are consistent with the actual dynamic rock breaking and pore forming process,which lends credence to the present results and indicates that they could be used as a reference for the future optimization of systems based on the multi-hole combined external rotary bit technology.

Spectral and statistical analysis of bow wave breaking characteristics of KCS ship

Bow wave breaking is a common phenomenon during ship navigation,especially at a high speed,involving complex physical mechanism such as interface mixing,air entrainment,and jet splashing.This study uses the delayed detached eddy simulation(DDES)turbulence model on the OpenFOAM platform to simulate flow around a KRISO Container Ship(KCS)model for a Froude number of 0.35,examining trim angles of 0°,0.5°,1°.This paper analyzes the statistical and power spectral density(PSD)characteristics of bow wave heights.The analysis shows root mean square(rms)and mean difference between top and bottom views indicate wave breaking.As the trim angle increases,peaks of rms in the bottom view become much higher than that in the top view,reaching 38%at 1°.PSD analysis reveals that resistance and wave height periods differ by no more than 5%,with small-scale structures like jetting and splashing causing non-dominant periodic and high-frequency wave height variations.

Vibrating-Rocking Motion of Caisson Breakwater Under Breaking Wave Impact

The possible motions of a caisson breakwater under dynamic load excitation include vibrating, vibrating-sliding and vibrating- rocking motions. The models of vibrating motion and vibrating-sliding motion have been proposed in an early paper. In this paper, a model of vibrating- rocking motion of caisson breakwaters under breaking wave impact is presented, which can be used to simulate the histories of vibrating-rocking motion of caisson breakwaters. The effect of rocking motion on the displacement, rotation, sliding force and overturning moment of breakwaters is investigated, In case the overturning moment exceeds the stability moment of a caisson, the caisson may only rock. The caisson overturns only in case the rocking angle exceeds the critical angle, It is shown that the sliding force and overturning moment of breakwaters can be reduced effectively due to the rocking motion, It is proposed that some rocking motion should be allowed in breakwater design.

Existence of spontaneous symmetry breaking in two-lane totally asymmetric simple exclusion processes with an intersection

We study two-lane totally asymmetric simple exclusion processes(TASEPs)with an intersection.Monte Carlo simulations show that only symmetric phases exist in the system.To verify the existence of asymmetric phases,we carry out a cluster mean-field analysis.Analytical results show that the densities of the two upstream segments of the intersection site are always equal,which indicates that the system is not in asymmetric phases.It demonstrates that the spontaneous symmetry breaking does not exist in the system.The density profiles and the boundaries of the symmetric phases are also investigated.We find that the cluster mean-field analysis shows better agreement with simulations than the simple mean-field analysis where the correlation of sites is ignored.

Parameterization of Wave Breaking Probability and Whitecap Coverage

The model for whitecap coverage and wave breaking probability are parameterized by the dimensionless wind fetch X^-. This paper aims at replacing X^- with other parameters such as the average wave period T^-, wind speed U10 or wave age ξ in order to improve the suitability and convenience of the model for application. First, W and B are expressed in terms of T^- and U10, which are relatively easy to measure in the field. Further, U10 is replaced with the friction velocity U. by use of the empirical relationship. As wave age has been widely used to parameterize spectral models of ocean waves and air-sea fluxes, W and B are then expressed as a simple function of wave age, respectively. The new forms of the model obtained are W= 1 - Ф（3.02ξ0＂76） and B = exp（ - 4.54ξ^1.52） . The two forms are mere applicable in pracrice, since ξ is relatively easy to measure or determine from wave and wind records. Comparisons between these expressions and data collected from published literature are made and agreement is fairly good.

试论Breaking训练中力量训练的重要性

Breaking诞生在二十世纪六十年代末,是美国黑人城市贫民的舞蹈,Breaking在许多青少年和帮派成员中非常流行,而breaking就是从街头开始的。通常,敌对团体中最好的舞者常用Battle(斗舞)的方式进行来展示舞蹈的智慧,而不是采用武力。在Battle(斗舞)中舞者需要表达自己的态度,通过日常各种力量训练使肢体力量的动律足以表达自身的态度。本文在了解Breaking的含义、起源、发展的基础之上,分析整理了有关于力量训练的内容,并以此为基础探讨了Breaking的力量训练内容,探析力量训练在Breaking舞蹈课堂中的现状,并分析力量训练对Breaking的重要性,从而体现力量训练对于舞蹈而言的至关重要性。

Unraveling links between aging,circadian rhythm and cancer:Insights from evidence-based analysis

Aging and circadian rhythms have been connected for decades,but their molecular interaction has remained unknown,especially for cancers.In this situation,we summarized the current research actuality and problems in this field using the bibliometric analysis.Publications in the PubMed and Web of Science databases were retrieved.Overall,there is a rising trend in the publication volume regarding aging and circadian rhythms in the field of cancer.Researchers from USA,Germany,Italy,China and England have greater studies than others.Top three publication institutions are University of California System,UDICE-French Research Universities and University of Texas System.Current research hotspots include oxidative stress,breast cancer,melatonin,cell cycle,calorie restriction,prostate cancer and NF-κB.In conclusion,results generated by bibliometric analysis indicate that many approaches involve in the complex interactions between aging and circadian rhythm in cancer.These established and emerging research directions guide our exploration of the regulatory mechanisms of aging and circadian rhythms in cancer and provide a reference for developing new research avenues.

Intelligent Diagnostic Method for Ageing Analysis of Transformer

The fuzzy method is proposed for ageing analysis of transformer. The fuzzy controller is used for various input and one output, strictly depends on the number of membership function and there rule base and the type of the defuzzification method. The ageing of transformers is influenced by short term and long term over loads, number and intensity of short circuits, incidence of lightning, and internal faults. The recent development of various techniques for detecting the incipient fault conditions have been improved to some extent;the life expectancy of transformers by resorting to corrective actions in time. The ageing behavior is likely to be different for different types of transformers. The life span of the transformer, thus depends initially on the design and quality of manufacture and later on service conditions and maintenance standard, these factors vary considerably and affect the useful span of service life which therefore needs to be taken into account for residual life assessment. During the natural ageing of transformers, the insulation of winding deteriorates. Cellulose insulation degrades due to heating or electrical breakdown which is dissolved in oil. Hence, the chemical analysis of the Transformer oil gives evidence of changes that are taking place in the winding insulation during operation. Deterioration in transformer cellulose decreases both its electrical and mechanical strength. In this paper a novel fuzzy based algorithm has been implemented on three samples of power transformer oil.

基层老年慢性病患者心血管疾病综合发生风险的影响因素研究

背景心血管疾病是造成我国居民死亡和疾病负担的首要病因,防控形势严峻。心血管疾病风险影响因素管理是预防心血管疾病的重要基础。但目前国内外应用单导联可穿戴心电设备针对基层老年慢性病患者心血管疾病发生风险的影响因素调查研究较少,且在既往研究中也未以整体观对患者包含不同数量风险的变量重要性进行排序。目的分析基层管理的65岁以上老年慢性病患者心血管疾病综合发生风险的影响因素,为基层心血管疾病综合防控提供客观依据及帮助。方法选取2021年12月—2022年9月宁夏回族自治区26家基层医疗卫生机构的3039例65岁以上+高血压、糖尿病、冠心病其中至少1种慢性病的患者为研究对象。依据72 h心电图分析结果划分为正常组632例、风险组2407例。分析两组患者基本资料,确定最佳λ值,绘制模型,采用LASSO回归和多因素Logistic回归分析探讨老年慢性病患者心血管疾病综合风险影响因素;并对影响心血管疾病综合风险及包含不同数量风险的变量排序。结果两组患者年龄、性别、BMI、教育程度、职业、城乡分布、吸烟、运动、冠心病+糖尿病、高血压+冠心病及糖尿病比较,差异均有统计学意义(P<0.05);最佳λ值为0.01568531。LASSO回归和多因素Logistic回归模型分析显示年龄、BMI、城乡分布、吸烟、高血压+冠心病+糖尿病是心血管疾病综合风险的影响因素(P<0.05)。受试者工作特征曲线下面积(AUC)=0.650(95%CI=0.627~0.673,P<0.001)。影响综合风险及不同数量风险种类变量排序前五位的分别为:年龄、BMI、城乡分布、饮茶、运动;年龄、高血压+冠心病、性别、城乡分布、吸烟;年龄、高血压+冠心病、性别、BMI、城乡分布;糖尿病+冠心病、年龄、高血压+冠心病、高血压+冠心病+糖尿病、高血压+糖尿病。结论年龄、BMI、城乡分布、吸烟、高血压合并冠心病及糖尿病是65岁以上+慢性病患者发生心血管疾病风险的影响因素。除年龄外,BMI及生活习惯对心血管疾病综合风险的发生影响较为重要,随着+风险种类数量的增多,慢性病尤其慢性病共病的影响增强。基层医护团队应以单导联可穿戴设备为载体定期对老年慢性病患者进行心血管疾病综合发生风险管理,其不但可高效、低成本的实现心血管疾病发生风险的一级、二级预防及健康管理,并可加速基层医疗服务应加快从不连贯的诊疗服务向全程健康管理的转变。

基于健康社会决定因素的宁夏中老年人慢性病共病的影响因素研究

背景人口老龄化进程日益加快,中老年人健康问题突出。慢性病共病严重威胁中老年人的健康和生活质量,阻碍健康中国行动的进展,探讨其与健康社会决定因素的关系具有积极意义。目的了解宁夏中老年人慢性病共病情况及健康社会决定因素情况,分析中老年人健康社会决定因素与慢性病共病的关联,为中老年慢性病共病患者的健康管理和干预策略制定提供参考。方法采用多阶段分层随机抽样方法于2022-06-27—08-27调查宁夏石嘴山市、银川市、固原市的10个区/县1997名中老年人的健康相关数据,应用Apriori算法分析宁夏地区中老年人的共病模式,采用非条件Logistic回归分析探讨宁夏中老年人慢性病共病与健康社会决定因素的关联性。结果宁夏地区中老年人慢性病共病人数418例,慢性病共病率20.9%;关联规则结果显示有14条共病模式,其中11条与冠心病有关,9条与高血压有关,9条与糖尿病有关;非条件Logistic回归分析结果显示,年龄≥60岁、子女数量为2~3个、已建立健康档案、工作状况为离退休和无业、养老保险为城乡居民基本养老保险的中老年人慢性病共病率较高(P<0.05),夜间睡眠时长为7~8 h和>8 h、大专及以上文化水平的中老年人慢性病共病率较低(P<0.05)。结论中老年慢性病共病的影响因素涉及个体、社区、社会各个方面,建议从多维度对慢性病共病患者进行干预,以期提高其健康水平。

新劳动的核心特质及其中国的时代呈现

随着第四次技术革命的到来,各类事物不再困于特定系统中,而是被要素化,随着系统边界的打破被释放出来,并与新要素联结在一起,使劳动呈现出各种新状态。知识劳动、创意劳动、创业劳动、数字劳动等新劳动推动了科技创新与新质生产力的发展。新劳动的核心特质是破壁性与关联性:从劳动方式看,其破除了各类劳动、要素的边界,要求总体性劳动实现高位复归;从劳动时空看,其在时空交错、时空侵占机制作用下,不断突破着生活与工作、虚拟与真实、本地与全球、当下与未来之间的次元壁;从劳动组织和制度看,自上而下的制度规章与自下而上的自主工作加以结合,劳雇双方的身边边界变得模糊,氛围、体验等非制度因素成为激发生产活力的关键。在中国式现代化的进程中,新劳动的出现也对劳动社会学研究提出了破壁与联结的新要求。

近10年国内老年血液透析研究热点的可视化分析

目的:分析我国老年血液透析患者的研究现状、热点及趋势。方法:检索中国知网(CNKI)、万方数据库、维普数据库、中国生物医学文献数据库近10年发表的老年血液透析相关文献,应用CiteSpace 6.2.R7对相关研究的作者、研究机构、关键词进行可视化分析。结果:检索出符合要求的文献1545篇,文献发文量保持平稳增长,2018年为发文高峰;发文期刊多为医疗类期刊,发文量最多的作者为罗洋、陈文和郭一丹,各6篇;发文量较多的地区集中在北京、上海、南京和四川。老年血液透析研究热点集中在治疗、用药、预后和并发症的管理。结论:老年血液透析研究内容较广泛、热点不突出;研究领域内作者及机构合作不紧密,未形成稳定的核心作者群;目前的研究水平发展较不均衡,护理研究内容和质量有待加强。

柴达木盆地古近系下干柴沟组上段碎屑锆石U-Pb测年及盆山耦合探讨

柴达木盆地被祁连山、阿尔金山及昆仑山所环绕,盆地古近系下干柴沟组(E32)地层独特的岩性和沉积格局指示了复杂盆山体系和源区多样成因。本文选取了盆地内部不同构造带5口钻井下干柴沟组的中粗砂岩样品,利用碎屑锆石U-Pb定年等分析方法对柴达木盆地进行了构造、物源系统分析。研究结果表明,位于祁连山前的XX-1井样品下干柴沟组锆石年龄介于2692~156Ma之间,主要峰值年龄为448Ma和249Ma,L6-1井样品锆石年龄介于2693~220Ma之间,主要峰值年龄为499Ma和415Ma;位于盆地西部沉降中心内部的YIT-1井样品下干柴沟组锆石年龄介于2796~266Ma之间,主要峰值年龄为423Ma和255Ma;阿尔金山前的N-105井样品下干柴沟组锆石年龄介于2481~242Ma之间,主要峰值年龄为422Ma和259Ma,N-109井样品锆石年龄介于2638~228Ma之间,主要峰值年龄为444Ma和246Ma。通过与主要源区年龄对比可知,盆地不同构造带下干柴沟组的物源差异较大,靠近祁连山前的XX-1井、L6-1井的物源主要来自于祁连山内部;位于阿尔金山前相邻的N-105、N-109井物源主体来自于阿尔金山内部,但N-109井存在祁连山物源贡献;柴西坳陷内部YIT-1井物源受祁连山及东昆仑共同控制。物源分析结果表明祁连山在古近纪已大规模隆升,并且作为青藏高原北部边界为柴达木盆地持续提供物源;阿尔金山及昆仑山在下干柴沟组沉积时期已经形成雏形,但并未大规模隆升,造成了山前带复杂的物源体系。

1225例新型冠状病毒感染老年患者证候规律研究

目的探索老年群体新型冠状病毒感染常见证候分类及特征,为临床辨治提供参考。方法采集四川省内6家三甲医院的新型冠状病毒感染的老年患者的四诊信息,构建数据库。运用隐结构法的Lantern 5.0软件,基于双步隐树分析,构建隐结构模型,通过综合聚类提取新型冠状病毒感染常见证候。采用SPSS 23.0软件进行因子分析和系统聚类分析,推断潜在证候。结合不同方法结果和专业知识确定新型冠状病毒感染证候分类。结果共纳入1225例新型冠状病毒感染患者,共收集103个症状。纳入分析频次≥40的59个症状构建隐结构模型,得到15个隐变量,综合聚类得到4种常见证候,分别为邪袭肺卫证、邪热蕴肺证、湿邪困脾证、阴虚夹湿证。得到19个公因子,用公因子进行系统聚类分析,推断出4个常见证候。结合不同方法和专业知识最终确定4种常见证候及特征。结论四川地区老年群体新型冠状病毒感染常见证候为邪袭肺卫证、邪热蕴肺证、湿邪困脾证、阴虚夹湿证。研究结果较客观地反映了四川地区老年患者新型冠状病毒感染的实际情况,可为四川地区老年患者新型冠状病毒感染辨证治疗提供参考。

关中平原城市群韧性空间关联网络及其影响因素研究

基于熵值法测度2011—2020年关中平原城市群11个地市的城市韧性综合评价指数,分析其韧性时空演化特征,并采用社会网络分析法和二次指派程序剖析其空间关联网络结构及影响因素。结果表明:(1)关中平原城市群内各城市韧性整体呈上升趋势,韧性水平呈现出从省会开始向外围降低的态势。(2)城市群韧性网络结构变得更加复杂和稳健,但地区间韧性联系呈现较强的层级性特征,也尚未完全实现互相联通的状态。(3)西安市、咸阳市、铜川市的中心性较强,能够对周边或边缘城市产生较多资源溢出,城市群“核心-边缘”结构明显。(4)地理空间邻近、经济发展水平、对外开放度、政府财政支持、科技发展水平、交通基础设施的差异均显著影响城市群韧性空间网络结构的变化。关中平原城市群可通过建设城际数字化管理与交流平台、加强交通网络建设、增加科技创新投入等途径提升城市韧性与城市间的关联性。

恶性肿瘤同步放化疗患者的营养状况及其影响因素

目的调查恶性肿瘤同步放化疗患者营养状况并分析其影响因素。方法以自设问卷方式收集2019年3-5月于北京大学肿瘤医院行同步放化疗恶性肿瘤患者的相关临床资料。采用患者参与主观整体评估量表(PG-SGA)评估患者的营养状况,并分析其影响因素。结果共收回有效问卷150份。150例患者的PG-SGA评分中位数为6.0(3.0,11.0)分。56例(37.3%)患者重度营养不良,49例(32.7%)患者中度营养不良。单因素分析显示,老年、食管癌或头颈部肿瘤、Ⅳ期、放疗次数>15次、化疗次数>4次、紫杉醇+铂或铂类单药治疗方案是患者营养不良的影响因素(Z=-3.839~-2.087,P<0.05)。二元logistic回归分析显示,老年、食管癌或头颈部肿瘤、放疗次数>15次是患者重度营养不良的独立危险因素(P<0.05)。结论恶性肿瘤同步放化疗患者营养不良比例高,尤其是老年、食管癌或头颈部肿瘤、同步放化疗后期患者。医务人员应动态评估、监测患者营养状况,并及时干预。