Effect of Changing Front Top Roller Pressure of Drafting Zone of a Ring Frame on the Quality of Cotton-Flax Blended Yarn

Pressure applied on the top roller of drafting zone is a vital factor on which the quality of ultimate yarn depends. Drafting zone is needed to reduce the mass per unit length of input material. Appropriate contact of top rollers with bottom rollers is necessary to ensure proper drafting. In this paper, the effects of different front top roller pressure of drafting zone on the quality of 20Ne cotton-flax blended yarns (C:L = 45:55) were studied. It was observed that a higher pressure value gives a lower co-efficient of mass variation, imperfections, hairiness and higher evenness, tenacity, elongation properties.

A machine learning approach for the prediction of pore pressure using well log data of Hikurangi Tuaheni Zone of IODP Expedition 372,New Zealand

Pore pressure(PP)information plays an important role in analysing the geomechanical properties of the reservoir and hydrocarbon field development.PP prediction is an essential requirement to ensure safe drilling operations and it is a fundamental input for well design,and mud weight estimation for wellbore stability.However,the pore pressure trend prediction in complex geological provinces is challenging particularly at oceanic slope setting,where sedimentation rate is relatively high and PP can be driven by various complex geo-processes.To overcome these difficulties,an advanced machine learning(ML)tool is implemented in combination with empirical methods.The empirical method for PP prediction is comprised of data pre-processing and model establishment stage.Eaton's method and Porosity method have been used for PP calculation of the well U1517A located at Tuaheni Landslide Complex of Hikurangi Subduction zone of IODP expedition 372.Gamma-ray,sonic travel time,bulk density and sonic derived porosity are extracted from well log data for the theoretical framework construction.The normal compaction trend(NCT)curve analysis is used to check the optimum fitting of the low permeable zone data.The statistical analysis is done using the histogram analysis and Pearson correlation coefficient matrix with PP data series to identify potential input combinations for ML-based predictive model development.The dataset is prepared and divided into two parts:Training and Testing.The PP data and well log of borehole U1517A is pre-processed to scale in between[-1,+1]to fit into the input range of the non-linear activation/transfer function of the decision tree regression model.The Decision Tree Regression(DTR)algorithm is built and compared to the model performance to predict the PP and identify the overpressure zone in Hikurangi Tuaheni Zone of IODP Expedition 372.

Multiphysics processes in the interfacial transition zone of fiber-reinforced cementitious composites under induced curing pressure and implications for mine backfill materials: A critical review

The mesoscale fiber-matrix interfacial transition zone(FM-ITZ) under induced curing pressure plays a key role in the effectiveness of fiber reinforcement and the engineering application of fiber-reinforced cementitious composites(FRCCs). This critical review establishes the link among induced curing pressure(i.e., external loading condition), multiphysics processes(i.e., internal governing mechanism), and interface behavior(i.e., material behavior) for FRCC materials through analysis of the state-of-the-art research findings on the FM-ITZ of FRCC materials. The following results are obtained. For the mechanical process, the induced curing pressure changes the stress state and enhances multicracking behavior, which can strengthen the FM-ITZ. For the hydraulic process, the strengthened seepage of the FM-ITZ under induced curing pressure weakens the effective stress and exaggerates the deficiency in water retention capacity between the bulk matrix and the FMITZ. For the thermal process, the induced curing pressure causes a steep temperature gradient in the FM-ITZ and thus influences the temperature evolution and thermally-induced microcracks in the FM-ITZ. For the chemical process, the induced curing pressure enhances hydration kinetics and results in the formation of additional hydration products in the FM-ITZ. Moreover, recommendations are proposed on the basis of findings from this review to facilitate the implementation of fiber reinforcement in cemented paste backfill technology.

PRESSURE DISTRIBUTION ON THE GRIP ZONES IN THE CONFORM PROCESS

The pressure distribution on the grip zones in the CONFORM process has been analysed by means of the slab method, and from the above results the forces applied to the shoe were derived. It is shown that the pressure along the segment increases powerfully with θ increasing in the primary grip, and increases linearly with θ increasing in the extrusion grip. Thus, it can offer mechanics parameters for the operating techniques and CONFORM machine design.

Spatiotemporal Pattern of Cultivated Land Pressure and Its Influencing Factors in the Huaihai Economic Zone, China

Cultivated land pressure represents a direct reflection of grain security. Existing relevant studies rarely approached the spatiotemporal pattern of cultivated land pressure or the spatial heterogeneity of its influencing factors from the level of economic zones.Taking the Huaihai Economic Zone(HEZ), China for case analysis, this study investigated the spatiotemporal pattern of cultivated land pressure in diverse periods from 2000 to 2018 based on a modified cultivated land pressure index and spatial correlation models. On this basis, it explored the influencing factors of the spatial differentiation of cultivated land pressure in the late stage of the study using geographical detector as well as multi-scale geographically weighted regression model. The results indicated that: 1) in the study period, the global cultivated land pressure index of the study area decreased gradually, but cultivated land pressure increased locally in a significant way, especially in the central and southern Shandong Province;2) the spatial pattern of cultivated land pressure manifested global clustering features. Hot and secondary-hot spots presented a narrowing and clustering trend, whereas cold and secondary-cold spots manifested a spreading and clustering trend;3) average slope, the proportion of non-grain crops, population urbanization rate, and multiple cropping index have significant effects on the spatial differentiation of cultivated land pressure. The former three factors were positively correlated with cultivated land pressure, and the last factor was negatively correlated with cultivated land pressure;and 4) the amount of cultivated land has increased in the central and southern Shandong Province through land consolidation which, nonetheless, failed to improve the grain production. In regards to major grain producing areas similar to the HEZ in China, the authors suggest that great importance should be given to the balance of the quality and quantity of cultivated land, the optimization of agricultural production factors and the rational control of non-grain crops, thus providing a powerful guarantee for grain security in China.

Identification of the Breach of Short-Term Rental Regulations in Irish Rent Pressure Zones

The housing crisis in Ireland has rapidly grown in recent years. To make a more significant profit, many landlords are no longer renting out their houses under long-term tenancies but under short-term tenancies. Regulating rentals in Rent Pressure Zones with the highest and rising rents is becoming a tricky issue. In this paper, we develop a breach identifier to check short-term rentals located in Rent Pressure Zones with potential breaches only using publicly available data from Airbnb (an online marketplace focused on short-term home-stays) and Irish government websites. First, we use a Residual Neural Network to filter out outdoor landscape photos that negatively impact identifying whether an owner has multiple rentals in a Rent Pressure Zone. Second, a Siamese Neural Network is used to compare the similarity of indoor photos to determine if multiple rental posts correspond to the same residence. Next, we use the Haversine algorithm to locate short-term rentals within a circle centered on the coordinate of a permit. Short-term rentals with a permit will not be restricted. Finally, we improve the occupancy estimation model combined with sentiment analysis, which may provide higher accuracy.

Optimal depth of in-situ pressure-preserved coring in coal seams considering roadway excavation and drilling disturbance

Using pressure-preserved coring technique to determine in-situ gas content provides a more precise assessment of gas resource reserves and safeguard of mining safety in coal seams. How coring technique and depth affect the determination of gas content is unclear due to borehole zoning rupture caused by roadway excavation and drilling disturbance. To this end, a proposed coupling model of stress distribution and gas migration was simulated and validated by FLAC^(3D) and COMSOL Multiphysics considering superposition effects of roadway excavation and drilling disturbance. The findings indicate that the roadway surrounding rock displays distinct zoning features including stress relief zone, stress concentration zone that is composed of plastic zone, elastic zone, and original stress zone;and the broken situations depending on the borehole peeping are consistent with the corresponding simulation results.On this basis, this study proposes a set of drilling coring depth calculation and prediction model for the gas desorption affected area under engineering disturbance. Optimal depth of coring drilling is not only approach to the in-situ coal bulk, but also can get the balance of the drilling workload and cost controlling. According to the typical mine site geological conditions and the numerical simulation results in this study, if the roadway excavation time is ~1 year, it is recommended that the pressure-preserved coring depth should be greater than 17 m.

富水区水工隧洞外水压力降压措施研究

外水压力是影响隧洞稳定及衬砌结构安全性的重要因素,特别是对富水地层深埋水工隧洞,高外水压力给衬砌设计带来巨大挑战.目前隧洞排水降压措施没有统一的标准,且主要聚焦于对衬砌外水压力的影响,对渗流场的影响分析还有待加强.本文依托滇中引水工程松林隧洞,借助ABAQUS软件开展隧洞围岩及衬砌结构流固耦合分析,分析在不同灌浆圈参数及排水布置方案下,隧洞渗流场及衬砌外水压力的变化规律.研究结果表明:通过改变灌浆圈厚度或降低灌浆圈的渗透性均可有效降低衬砌外水压力并减小隧洞开挖对渗流场的影响;布置排水孔亦能有效降低衬砌外水压力,且对距离排水孔越近降压效果越显著,离排水孔越远降低幅度越小且对渗流场产生较大影响,建议在实际工程中应采取堵排结合的措施来降低外水压力,并对排水孔及灌浆圈开展优化设计,以得到最优减压效果.

西南天山榴辉岩相脉体记录的俯冲带多期流体作用

俯冲带是全球最大的物质循环系统,控制着壳幔相互作用、岛弧岩浆作用、成矿物质聚集和全球元素循环等诸多重要的地质过程。俯冲带流体作为板片向上覆地幔楔进行物质传输的重要媒介,在上述地质过程中扮演着关键角色。基于岛弧火山岩地球化学特征、高温高压实验、相平衡模拟,以及高压-超高压变质岩的研究,我们对俯冲带流体基本特征及其地球化学行为已经有了较为深刻的认识,然而,目前对俯冲带流体作用的复杂性,如多期流体作用,还缺少深入的理解。本文对西南天山高压-超高压变质带榴辉岩中一条含石英-绿帘石-铁白云石-硫化物的高压脉开展了详细的岩石学、地球化学研究。脉体中有绿辉石、铁白云石、金红石等特征高压矿物的产出,暗示其代表的流体作用发生于高压条件下。脉体与主岩榴辉岩界线截然,之间无蚀变带/过渡带/交代晕产出,说明主岩榴辉岩与迁移流体之间没有发生显著的水-岩交换反应。脉体矿物(如绿帘石、铁白云石、黄铁矿等)的多期生长特征及其成分差异研究揭示出至少三期流体作用。前两期流体作用均发生于高压条件下,特征如下:(1)两期流体分别以两期矿物组合(Ep^(1)-Dol^(1)-Py^(1)组合以及Ep^(2)-Dol^(2)-Py^(2)组合)为代表,在第二期流体作用下,第一期流体沉淀的矿物(如Dol^(1)等)发生了明显的溶解-再沉淀作用;(2)两期流体性质均以富Ca、Si,含CO_(2)、S为特征,第一期流体较第二期流体富Fe贫Mg,富Ni贫Co,富轻稀土元素(LREE);(3)两期黄铁矿的δ^(34)S值分别为-8‰和-5‰,暗示这两期流体均主要来源于俯冲沉积物,且第二期流体可能有更多俯冲洋壳或蛇纹岩脱水流体的参与;(4)两期流体作用下,碳酸盐矿物和硫化物显示出耦合共生的特点,暗示C、S在流体作用下可能具有协同演化(如溶解-迁移-沉淀)的关系。第三期流体作用以绿帘石+铁白云石反应生成方解石+绿泥石、绿帘石边部(与黄铁矿相邻处)发生成分改造为特征,流体作用发生在高压岩石折返的退变质阶段,记录了退变质流体的信息。本研究通过榴辉岩高压脉体中多期矿物生长的特征,揭示了俯冲带内多期流体作用,对深入理解俯冲带流体性质、流体来源、以及俯冲带关键挥发分元素的耦合演化信息,具有重要的科学意义。

航改燃机燃烧室掺氢燃烧特性研究

日益严格的碳减排要求对动力行业的发展产生了重要影响,厘清燃气轮机燃烧室掺氢燃烧特性成为亟待突破的研发重点。该文选用典型航改燃机燃烧室,在保持燃料总发热量不变的条件下,采用数值模拟探究掺氢体积比对燃烧室实际工况下流场结构、燃烧产物等方面的影响规律,并分析流场动态特性的变化。结果表明,随掺氢比的提升,燃烧室前端温度升高,气体体积膨胀导致中心回流区缩小,CO_(2)排放降低,高温回流产物逐渐远离燃料喷嘴。同时,喷嘴附近热释率增大,压力波动加剧,可能增强燃烧不稳定性进而影响结构安全性。结果可为现有燃机掺氢燃烧改造以及未来氢燃机设计提供一些指导。

综采工作面顶板切顶卸压沿空留巷围岩控制技术

为解决沿空掘巷存在大量煤柱损失、影响采掘接替等问题,同时防止回采过程中巷道产生严重变形,决定采用切顶卸压和综合支护方案对巷道围岩进行有效控制。针对2号煤层21206综采工作面复合顶板,采用理论分析和FLAC^(3D)数值模拟方法,确定了切顶卸压参数,其切顶角度为15°,切顶深度为9 m;将沿空巷道划分为超前支护区、滞后临时支护区和成巷稳定区,并采取不同的支护形式。综合支护方案实施,沿空留巷60 d内顶板下沉量最大值降低49.3%;两帮移近量最大值降低57.3%;工作面多回收煤炭15.6万t,并节省1条长度为1710 m的掘进巷道,并节省施工工期6个月,具有显著的经济效益。

Effects of Tectonic Force on Hydrostatic Pressure in Crust

The research into the hydrostatic pressure in the crust has been previously conducted from the viewpoint that the hydrostatic pressure is equal to the gravity, based on the fact that the hydrostatic pressure is derived mainly from the gravity of its overlying rocks. In this paper, the stress state of any point in the crust is suggested to have been caused by both the gravity and the tectonic force. The author proposes that the hydrostatic pressure is a combination or superposition of two isotropic stresses in the tectonic force and gravity stress fields. The results obtained with a finite element simulation indicate that the additional hydrostatic pressure borne by rocks decreases gradually from the compression zone ( p s c), the shear zone ( p s sh ) to the tensile zone ( p s t), and that the difference in the additional tectonic hydrostatic pressure between these deformed zones tends to increase, following the increase in the absolute value and/or the difference in external forces between different directions. This paper presents the foundation for the research into the tectonic physicochemistry.

Deformation and failure study of surrounding rocks of dynamic pressure roadways in deep mines

In order to understand the change rules of stress-displacement in surrounding rocks of dynamic pressure roadways in deep mines and to obtain a theoretical basis for analyses of roadway stability and designs of support, we established a coupling equation of adjacent rock strength, mining stress and supporting resistance on the basis of an elastic-plastic theory of mechanics. We obtained an analytical solution for stress and displacement distribution of elastic and plastic regions in surrounding rock of dy-namic pressure roadway.. Based on this theory, we have analyzed the changes in stress-displacement in elastic and plastic regions of surrounding rocks of dynamic pressure roadways in the Haizi Coal Mine. The results show that: 1) radial and tangential stress change violently within the first 4 m from the inner surface of a roadway after excavation; radial stress increases while tangential stress decreases within a range of about 6 m from the inner surface of the roadway as a function of q3; 2) radial and tangential stress increase with an increase in the mining pressure coefficient k; the increase in the rate of tangential stress is greater than that of ra-dial stress; 3) the radial displacement of the inner surface of roadways decreases with an increase in q3, provided that k remains unchanged.

Research of the electrical anisotropic characteristics of water-conducting fractured zones in coal seams

Water flooding disasters are one of the five natural coal-mining disasters that threaten the lives of coal miners. The main causes of this flooding are water-conducting fractured zones within coal seams. However, when resistivity methods are used to detect water-conducting fractured zones in coal seams, incorrect conclusions can be drawn because of electrical anisotropy within the water-conducting fractured zones. We present, in this paper, a new geo-electrical model based on the geology of water-conducting fractured zones in coal seams. Factors that influence electrical anisotropy were analyzed, including formation water resistivity, porosity, fracture density, and fracture surface roughness, pressure, and dip angle. Numerical simulation was used to evaluate the proposed electrical method. The results demonstrate a closed relationship between the shape of apparent resistivity and the strike and dip of a fracture. Hence, the findings of this paper provide a practical resistivity method for coal-mining production.

Upper Limit for Rheological Strength of Crust in Continental Subduction Zone:Constraints Imposed by Laboratory Experiments

The transitional pressure of quartz coesite under the differential stress and highly strained conditions is far from the pressure of the stable field under the static pressure. Therefore, the effect of the differential stress should be considered when the depth of petrogenesis is estimated about ultrahigh pressure metamorphic (UHPM) rocks. The rheological strength of typical ultrahigh pressure rocks in continental subduction zone was derived from the results of the laboratory experiments. The results indicate the following three points. (1) The rheological strength of gabbro, similar to that of eclogite, is smaller than that of clinopyroxenite on the same condition. (2) The calculated strength of rocks (gabbro, eclogite and clinopyroxenite) related to UHPM decreases by nearly one order of magnitude with the temperature rising by 100 ℃ in the range between 600 and 900 ℃. The calculated strength is far greater than the faulting strength of rocks at 600 ℃, and is in several hundred to more than one thousand mega pascals at 700-800 ℃, which suggests that those rocks are located in the brittle deformation region at 600 ℃, but are in the semi brittle to plastic deformation region at 700-800 ℃. Obviously, the 700 ℃ is a brittle plastic transition boundary. (3) The calculated rheological strength in the localized deformation zone on a higher strain rate condition (1.6×10 -12 s -l ) is 2-5 times more than that in the distributed deformation zone on a lower strain rate condition (1.6×10 -14 s -1 ). The average rheological stress (1 600 MPa) at the strain rate of 10 -12 s -1 stands for the ultimate differential stress of UHPM rocks in the semi brittle flow field, and the average rheological stress (550-950 MPa) at the strain rate of l0 -14 - 10 -13 s -l stands for the ultimate differential stress of UHPM rocks in the plastic flow field, suggesting that the depth for the formation of UHPM rocks is more than 20-60 km below the depth estimated under static pressure condition due to the effect of the differential stress.

Prediction Research of Deformation Modulus of Weak Rock Zone under In-situ Conditions

Weak rock zone (soft interlayer, fault zone and soft rock) is the highlight of large-scale geological engineering research. It is an important boundary for analysis of rock mass stability. Weak rock zone has been formed in a long geological period, and in this period, various rocks have undergone long-term consolidation of geostatic stress and tectonic stress; therefore, under in-situ conditions, their density and modulus of deformation are relatively high. Due to its fragmentary nature, once being exposed to the earth's surface, the structure of weak rock zone will soon be loosened, its density will be reduced, and its modulus of deformation will also be reduced significantly. Generally, weak rock zone can be found in large construction projects, especially in the dam foundation rocks of hydropower stations. These rocks cannot be eliminated completely by excavation. Furthermore, all tests nowadays are carried out after the exposure of weak rock zone, modulus of deformation under in-situ conditions cannot be revealed. In this paper, a test method explored by the authors has been introduced. This method is a whole multilayered medium deformation method. It is unnecessary to eliminate the relatively complete rocks covering on weak rock zone. A theoretical formula to obtain the modulus of deformation in various mediums has also been introduced. On-site comparative trials and indoor deformation modulus tests under equivalent density conditions have been carried out. We adopted several methods for the prediction researches of the deformation modulus of weak rock zone under in-situ conditions, and revealed a fact that under in-situ conditions, the deformation modulus of weak rock zone are several times higher than the test results obtained after the exposure. In a perspective of geological engineering, the research findings have fundamentally changed peoples' concepts on the deformation modulus of weak rock zone, provided important theories and methods for precise definition of deformation modulus of deep weak rock zone under cap rock conditions, as well as for reasonable engineering applications.

Surveying on two-zone height of sublevel strip mining

The site drilling packer permeability test and TEM to the 2100 workface in Gucheng coalmine determined the two-zone height under sublevel strip mining.The conclusion considers that the lying strata deterioration law of the strip mining is similar to that of the sublevel mining.Thus, against that the actually measured data lacked, it is feasible to refer to the reservation of the waterproof coal pillar in the neighbor coalmine under sublevel situation.However, it is necessary to further launch the research on lying strata deterioration law under sublevel striping mining for the purpose of providing the right foundation for the layout of the workface not mined so far and the reservation of the waterproof coal pillar in the mining area.

Effect of overburden pressure on determination of reservoir rock types using RQI/FZI,FZI^* and Winland methods in carbonate rocks

Rock typing is an important tool in evaluation and performance prediction of reservoirs.Different techniques such as flow zone indicator(FZI),FZI~*and Winland methods are used to categorize reservoir rocks into distinct rock types.Generally,these methods are applied to petrophysical data that are measured at a pressure other than reservoir pressure.Since the pressure changes the pore structure of rock,the effect of overburden pressure on rock typing should be considered.In this study,porosity and permeability of 113 core samples were measured at five different pressures.To investigate the effect of pressure on determination of rock types,FZI,FZI~*and Winland methods were applied.Results indicated that although most of the samples remain in the same rock type when pressure changes,some of them show different trends.These are related to the mineralogy and changes in pore system of the samples due to pressure change.Additionally,the number of rock types increases with increasing pressure.Furthermore,the effect of overburden pressure on determination of rock types is more clearly observed in the Winland and FZI~*methods.Also,results revealed that a more precise reservoir dynamic simulation can be obtained by considering the reservoir rock typing process at reservoir conditions.

Experimental Study on Seepage Characteristics of a Soil-Rock Mixture in a Fault Zone

A mixture of fault gouge and rubble taken out from a fault zone is used to prepare a S-RM(Soil-Rock Mixture)sample with rock block proportions of 20%,30%,40%,50%,60%and 70%,respectively.A GDS triaxial test system is used accordingly to measure the seepage characteristics of such samples under different loading and unloading confining pressures in order to determine the variation law of the permeability coefficient.The test results show that:(1)The permeability coefficient of the S-RM samples decreases as the pressure increases,and the decrease rate of this coefficient in the initial stage of confining pressure loading is obviously higher than in the semi-late period;(2)The permeability coefficient at different confining pressure levels presents a common trend as the rock block proportion is increased,i.e.,it decreases first then it increases(the permeability coefficient of the sample with rock block proportion 40%being the smallest,70%the largest);(3)In the stage of confining pressure unloading,the recovery degree of the permeability coefficient grows with the increase of rock block proportion(the recovery rate of S-RM sample with rock block proportion 70%reaches 50.2%);(4)In the stage of confining pressure loading and unloading,the sensitivity of the permeability coefficient to the rock block proportion displays the inverse“Z”variation rule(when rock block proportion reaches 60%,the sensitivity is highest);(5)In the stage of confining pressure loading,the relationship between the permeability coefficient and confining pressure can be described by an exponential relationship.