共查询到20条相似文献，搜索用时 15 毫秒
1.
Roll drafting, a mechanical operation attenuating fiber bundles to an appropriate thickness, is an important operation unit
for manufacturing staple yarns. It influences not only the linear density regularity of the slivers or staple yarns that are
produced, but also the quality of the textile product and the efficiency of the thereafter processes. In this research, the
dynamic states of the fiber bundle in the roll drafting zone were analyzed by simulation, based on the mathematical model
that describes the dynamic behavior of the flowing bundle. The state variables are the linear density and velocity of the
fiber bundles and we simulated the dynamics states of the bundle flow, e.g., the profiles of the linear density and velocity
in the draft zone for various values of the model parameters and boundary conditions, including the initial conditions to
obtain their influence on the dynamic state. Results showed that the mean velocity profile of the fiber bundle was strongly
influenced by draft ratio and process speed, while the input sliver linear density has hardly affected the process dynamics.
Velocity variance of individual fibers that could be supposed to be a disturbing factor in drafting was also influenced by
the process speed. But the major disturbance occurred due to the velocity slope discontinuity at the front roll, which was
strongly influenced by the process speed. Thickness of input sliver didn’t play any important role in the process dynamics. 相似文献
2.
This research reports on the variation behavior of the bundle thickness in a fiber bundle flow process, when the stochastic
perturbation occurs. The stochastic perturbation is specified by an autocorrelation function, which is generated on the basis
of the random phase spectrum. The profiles of the bundle thickness and velocity in a steady state were simulated, while the
mathematical model describing the fiber bundle flow dynamics is employed. Simulation results showed that a stochastic signal
with a specified autocorrelation function could apply to variations in the fiber bundle parameter and draft ratio. The distribution
profiles of the velocity and linear density of the fiber bundle were estimated under the auto-correlated perturbations. Disturbances
in the material parameter revealed a larger influence on the dynamic states of the fiber bundle flow than those in draft ratio. 相似文献
3.
The ring spinning method is broadly used for manufacturing various forms of yarns in various application fields in thanks
of the outstanding yarn characteristics and the well established processing technology. However, applying the ring spinning
for manufacturing functional yarn, for example, the core-spun yarn, often raises serious yarn quality problems. Especially,
surface defects make it difficult to extend the technology to various end-purposes. Dynamic state of the tension of fibers
in the spinning triangle that is considered as a triangular plane flow field plays an important role in causing the defects.
In this study, a theoretical model describing the tension behavior of the fibers in the triangular plane flow field was derived
and the availability of the model was tested experimentally. Results showed that the steady-state experiments brought good
corresponding results with those from the theory, which identifies the effectiveness of the theoretical model. The tension
dynamics of the fibers in spinning triangle could be expressed as a 1st order system, while the spinning triangle length and
the process velocity could majorly affect the tension dynamic characteristics. 相似文献
4.
Raju Seenivasan Rengasamy Raghavendran Guruprasad Patnaik Asis 《Fibers and Polymers》2005,6(2):146-150
In this paper, friction of air-jet textured yarns is investigated. Using a friction measuring apparatus fabricated in-house,
dynamic friction forces of the yarns under yarn-to-metal (YM) and yarn-to-yarn (YY) rubbing modes are measured. The influence
of processing variables of air-jet texturing viz., overfeed, air pressure, dry/wet texturing and normal/core-and-effect texturing
on dynamic friction is analysed. The results indicate that friction force increases with increasing rubbing speeds and yarn
input tension. YM dynamic friction decreases initially and then starts to increase at higher overfeeds. YY dynamic friction
increases with increasing overfeed. YM dynamic friction decreases with an increase in air pressure while an opposite trend
is observed for YY friction. Wet textured yarns have higher friction than dry textured yarns. Core wetted core-and-effect
textured yarns have higher friction than normal textured yarns. 相似文献
5.
6.
The compact spinning with suction groove can eliminate or decrease the spinning triangle by airflow compacting and shape condensing of the groove, so the yarn hairiness can be reduced effectively for long staple fiber. But the resistance torques produced by the spinning tension and the negative pressure of airflow influence the twist propagation. This paper analyzes variation of the friction coefficient between the fiber bundles and the groove. The transfer process of the moment of the spinning tension and airflow is studied in the variation of the friction coefficient. The expression of the resistance torque is established in the gathering area. The results show that the many factors influence the resistance torque, such as the horizontal friction coeffecient between the fiber bundles and the groove, the spinning tension and the negative pressure, as well as the angle between two suction holes etc. The proper negative pressure and the spinning tension can prevent twist propagation, and can reduce the yarn hairiness and improve the yarn quality. 相似文献
7.
冬小麦麦穗生长过程的模拟研究 总被引：2，自引：1，他引：2
为了实现小麦麦穗生长过程的可视化表达，以不同氮肥处理条件下不同类型小麦品种的两年田间试验为基础，通过连续观测并记载不同处理条件下的小麦主茎和分蘖麦穗形态指标（包括穗长、穗宽和穗厚），综合分析了小麦麦穗形态指标随生育进程和环境条件的变化规律，并利用系统分析方法和动态建模技术，构建了冬小麦麦穗生长过程的动态模拟模型。结果表明，麦穗的伸长过程符合S型曲线，而不同蘖位麦穗的最终长度符合二次曲线，且在不同氮肥处理之间均差异明显；采用Logistic方程描述了麦穗长度的动态变化过程，用二次曲线和线性方程定量描述了穗形的动态变化过程，同时采用旗叶的SPAD值量化了氮素对麦穗生长特征的影响；并利用不同小麦品种的田间试验资料对所建模型进行了测试和检验。结果显示，不同时期麦穗穗长、穗宽和穗厚预测值的平均RMSE分别为0．28、0．05和0．04cm。表明模型具有较强的动态预测性和可靠性，从而为进一步建立虚拟小麦生长系统奠定了基础。 相似文献
8.
Cashmere is a luxury fiber with high international demand. Australian cashmere fleece is shorn rather than hand combed, and
the shorn fleece contains a large quantity of coarse guard hair. Normally raw cashmere fleece is scoured first, followed by
dehairing to eliminate the coarse guard hair. But scouring the unwanted guard hair consumes a large quantity of water, and
increases the cost of cashmere processing in Australia. Ideally, the guard hair should be removed first and then the fine
cashmere fibers are scoured for further processing. This paper reports trial results on dehairing greasy rather than scoured
Australian cashmere fleece, with the aim of reducing scouring cost and water consumption. The quality of cashmere fibers after
the conventional dehairing process and the new greasy dehairing process has been assessed. The results indicate that fiber
quality from the greasy dehairing process is better than that from conventional scouring then dehairing process. 相似文献
9.
Thickness loss caused by static and dynamic loads is one of the most important quality factors in carpets. This property is influenced by pile yarn characteristics and carpet construction parameters. Exploring the relationship between thickness loss and effective factors is highly significant to optimize the selection of the variables. Soft computing approaches, which are potent data-modeling tools in capturing complex input-output relationships, seem to be the powerful technique to decipher the above-mentioned relationship. This paper presents two different modeling methodologies for predicting thickness loss of Persian hand-knotted carpets. At first, several topologies with different architectures were used to get the best neural-network model. Since, ANN model is a black box and did not succeed in indicating inter-relationship between input and output parameters, gene expression programming (GEP) is presented here as another intelligent algorithm to predict thickness loss of the carpets. Our study showed that, GEP model has a significant priority over the ANN. The correlation coefficient (R-value) and mean square error (MSE) for GEP model were 0.950 and 0.219 respectively, while these parameters were 0.707 and 0.510 for ANN model. This indicates the desirable predictive power of GEP algorithm. Based on the proposed models, the dominant parameter on thickness loss found to be knot density and content of slipe wool. 相似文献
10.
小麦叶鞘和节间生长过程的模拟研究 总被引：21，自引：2，他引：19
以5个不同株型小麦品种为供试材料,通过对冬小麦品种叶鞘和节间生长过程的连续观测和定量分析,构建了小麦叶鞘和节间生长过程的动态模拟模型。模型采用Logistic方程描述了叶鞘和节间的伸长动态;利用叶鞘与对应节间长度的比例关系模拟了不同节间的长度;利用节间粗与对应节间长的比例关系定量描述了不同节间的粗度。模型检验结果显示,不同叶鞘长、节间长和节间粗预测值的平均RMSE值分别为1.34、1.71和0.06 cm,表明本模型具有较好的预测性和可靠性。 相似文献
11.
Lignin, nature’s abundant polymer with a remarkably high carbon content, is an ideal bio-renewable precursor for carbon fiber production. However, the poor mechanical property of lignin-derived fibers has hindered their industrial application as carbon fiber precursor. In this work, process engineering through the application of computational modeling was performed to optimize wet-spinning conditions for the production of lignin precursor fibers with enhanced mechanical properties. Continuous lignin-derived precursor fibers with the maximum possible lignin content were successfully produced in a blend with polyacrylonitrile, as a wet-spinning process facilitator. Response surface methodology was employed to systematically investigate the simultaneous influence of material and process variables on mechanical properties of the precursor fibers. This allowed generating a mathematical model that best predicted the tensile strength of the precursor fibers as a function of the processing variables. The optimal wet-spinning conditions were obtained by maximizing the tensile strength within the domain of the developed mathematical model. 相似文献
12.
The present paper reports the detailed study on the splicing behavior of viscose staple fiber yarns made from ring, rotor,
friction and air-jet spinning technologies. The linear density of all the yearns was kept constant at 29.5 tex. The splicing
parameters like splicing pressure and duration of the splicing were taken as variables. Three levels of splicing pressure
at constant splicing duration and three levels of splicing durations at constant splicing pressure were considered. Splices
were introduced at all these levels for the four different technologies. These splices were tested for their tensile properties
and the properties of splices were evaluated in terms of retained splice strength (RSS) and splice break ratio (SBR). The
splice photographs were taken and splices were analyzed for their structure and for diameter profile along the length of the
splice. 相似文献
13.
Measuring tensile strength of nanofibers using conductive substrates and dynamic mechanical analyzer
Though the tensile strength of nanofibers is essential to determine their application fields, few studies have been conducted
on this topic, due to the difficulties involved in the preparation of single nanofiber tensile specimens, the manipulation
of the clamping device, and the sensing of the nano- force and strain. A bundle testing method was employed in this work to
measure the tensile strength of nanofibers. For this purpose, a conductive substrate was designed to hold several thousand
nanofibers extruded from a spinning nozzle and align them uniaxially during the electrospinning process. This substrate was
designed for a dynamic mechanical analyzer (DMA), because most DMAs are equipped with fine sensors sensitive enough to measure
a very small force and strain. Nylon 6 nanofibers were electrospun and collected on the substrate. Then, they were elongated
simultaneously in the DMA until they were fractured, showing that the aligned nanofibers have superior tensile strength and
modulus compared to their counterpart microfibers and thus suggesting that polymeric nanofibers have the potential to be used
as reinforcement fibers for composite materials. 相似文献
14.
大麻纤维受热过程中内部结构和物理性能的变化规律是大麻纺织、染整和大麻纤维增强复合材料加工工艺的理论依据,本论文通过对工业用大麻精干麻、原麻纤维的热学性能测试和受热后其束纤维相对断裂强度变化的测试实验,分析了工业用大麻纤维的分解温度、分解阶段和相对断裂强度的变化规律. 相似文献
15.
Haiyan Song Zhaoke Dong Lili Li Zengbin Lu Chao Li Yi Yu Xingyuan Men 《Journal of insect science (Online)》2021,21(1)
Apolygus lucorum (Meyer-Dür) (Hemiptera: Miridae) tends to feed on young plant tissues. To explore the relationship between stylet probing behaviors of adult A. lucorum and conditions of cotton leaves, we conducted an experiment using electropenetrography (EPG). Behaviors were recorded on four cotton varieties, in relation to thickness and biochemical traits of differently-aged leaves. Cotton leaf age had a significant effect on the probing behavior of A. lucorum but cotton variety did not. One-day-old leaves of A. lucorum received the highest mean number of stylet probes (penetrations) per insect, and longest mean durations per insect of combined stylet probing or its components, cell rupture and ingestion behaviors. All of the leaf traits (thickness and biochemical substances) were similar among these four cotton varieties. Leaf thickness had a significantly negative effect on the same four variables above. Gossypol and tannin also had a negative impact on combined probing duration. Redundancy analysis showed that the four EPG variables were closely related to nutrient substances (amino acids, sugar, and water) while they had the opposite relationship with plant defense substances (gossypol and tannin). On cotton in the seedling stages, A. lucorum fed more readily on the youngest, thinnest leaves in our no-choice EPG experiments. Nutrients and chemical resistance substances determined the probing duration of A. lucorum. Our findings can contribute to better understanding of patterns of feeding and host consumption by A. lucorum, ultimately improving cotton resistance to A. lucorum. 相似文献
16.
为了提高鲜叶分级机的筛分率,以柳叶种机采鲜叶为试验原料,对6CFJ-70型鲜叶分级机的关键技术参数进行了研究,利用Solidworks 2014对鲜叶分级机进行3D建模,基于离散元法建立鲜叶仿真颗粒模型和接触力学模型,设置关键仿真技术参数,运用EDEM 2018软件对鲜叶在锥形滚筒中的运动进行了数值模拟,得到影响筛分率的关键参数为锥形滚筒转速与倾角。为了对上述参数进行优化,以筛分率为目标函数,设计了2因素5水平的二次旋转正交组合试验,运用响应面法得到二次回归模型且通过了相关验证试验。结果表明,影响鲜叶分级效率的主要因素是锥形滚筒转速和锥形滚筒倾角。当锥形滚筒的转速为24 r·min-1,锥形滚筒倾角为6°时,鲜叶的筛分率为81.7%,具有较好的鲜叶分级效果,本文的研究内容可以为鲜叶分级机的设计与优化提供技术参考。 相似文献
17.
In line with the environmental protection trends of the 21st century, bamboo charcoal fiber is invented to meet the requirements
of the fields of science and technology. Its special functionalities, namely, antistatic, moisture adsorptive, perspiring,
antibacterial, deodorizing, anti-radiation, and far infrared properties make it extremely suitable for applications in medicine,
sports, and recreational fields, as well as an important breakthrough for environmentally-friendly textile materials. To achieve
rapid manufacturing, this study processes bamboo charcoal fibers by open-end (OE) rotor spinning. The Taguchi orthogonal array
is applied to the design of this experiment, and the significant factors of fibers quality are obtained through ANOVA in order
to facilitate the follow-up processes of quality control. The process prediction system is built based on the test data, and
is combined with the back-propagation neural network and the Levenberg-Marquardt (LM) algorithm in order to establish an OE
rotor spinning process prediction system. The rotor speed, feed speed, and winding speed are set as the network input parameters,
while the yarn strength, the hairiness, the unevenness, and the imperfections indicator (I.P.I.) are the output parameters.
Through network learning and training, this system reports a prediction error below 5 %, proving that this prediction system
has excellent predictability. 相似文献
18.
In connection with an effect on development of dynamic model of beat-up process, beat-up force and weaving condition, this study has investigated a correlation of 4 kinds of weaving factors (warp tension, weft thickness, weft density and shedding height) that affect beat-up force through an experimental method and analytic method. A simulator was developed to imitate beating, shedding, and insertion motions for weaving and the experiment was performed using the simulator. The experiments showed following results: First, the beat-up force increased proportionally as the warp tension increased. Second, the beat-up force increased with the increase of the weft thickness. Third, the beat-up force was exponentially inversely proportional to the weft density. Finally, the beat-up force was increased with the increase of the shedding height. Various experimental and simulation methods were performed to investigate the contribution of the principal weaving parameters to the beat-up force. 相似文献
19.
In a cross-lapper system, the carriage unit is used to make uniform web in appropriate width and thickness. Traditionally, this is a stable, sluggish system with large attenuation of the input in the steady state. In this paper, the modeling, stability, order reduction, dynamic analysis and controller design of a cross-lapper system for good nonwoven web quality will be presented to deal with this issue. A realizable controller is designed which can not only make the closed-loop system efficient for good tracking property but also can achieve the meaningful design objectives. The performance can be effectively shown from the computer simulation. 相似文献
20.
In this study, an artificial neural network (ANN) and a statistical model are developed to predict the unevenness of polyester/viscose
blended open-end rotor spun yarns. Seven different blend ratios of polyester/viscose slivers are produced and these slivers
are manufactured with four different rotor speed and four different yarn counts in rotor spinning machine. A back propagation
multi layer perceptron (MLP) network and a mixture process crossed regression model (simplex lattice design) with two mixture
components (polyester and viscose blend ratios) and two process variables (yarn count and rotor speed) are developed to predict
the unevenness of polyester/viscose blended open-end rotor spun yarns. Both ANN and simplex lattice design have given satisfactory
predictions, however, the predictions of statistical models gave more reliable results than ANN. 相似文献