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Effects of binder fibers and bonding processes on PET hollow fiber nonwovens

Fibers and Polymers 2013, Vol.14, No.4, 639-646639

Effects of Binder Fibers and Bonding Processes on PET Hollow Fiber

Nonwovens for Automotive Cushion Materials

Ki-Y oung Kim *, Song Jun Doh, Jung Nam Im, Won Y oung Jeong, Hyo Jin An, and Dae Y oung Lim

Department of Textile Convergence of Biotechnology & Nanotechnology, Korea Institute of Industrial Technology,

Ansan 426-793, Korea

(Received May 9, 2012; Revised August 13, 2012; Accepted August 25, 2012)

Abstract: In this study, nonwoven fabrics were developed for the replacement of polyurethane foams in car interiors, in particular, cushioning materials for car seats. Polyethylene terephthalate (PET) hollow fibers and two types of bicomponent binder fibers were used to manufacture automotive nonwovens by carding processes and then post-bonding processes, such as needle punching or thermal bonding. The physical and mechanical properties of nonwovens were thoroughly investigated with respect to the effects of binder fibers and bonding processes. The tensile strength and elongation for nonwovens were found to be significantly improved by combined needle punching and thermal bonding processes. In addition, the nonwoven cushioning materials were characterized in terms of hardness, support factors, and compressive and ball rebound resilience.The nonwovens showed greater hardness than the flexible PU foam. However, support factors over 2.8 for the nonwovens indicated improved seating comfort, along with better seating characteristics of greater resilience and air permeability in comparison with the PU foam.

Keywords: Nonwovens, Hollow fibers, Thermal bonding, Needle punching, PU foam, Cushion

Introduction

Technical textiles are fibrous structural materials and products manufactured primarily for their technical and performance properties rather than their aesthetic or decorative characteristics. They have been applied to diverse industries,including medicine, hygiene, sports, transportation, construction,and agriculture other than when intended for apparel,household, and furnishing end uses [1]. I n the last few decades, the technical textile industry has made significant progress, mostly through the advancement of nonwoven technologies with awareness of cost-effective processing and easily tailored properties to satisfy the demands of various industries.

Nonwovens are expanding the importance of technical textiles; in particular, the automotive industry is the largest consumer of technical nonwoven textiles, which are widely used in many forms for interiors and structural components for noise, vibration, and harshness (NVH) performance and weight reduction. I n the last few decades, the automotive industry has made significant progress in reducing vehicle weight through the development of new vehicle structural design and the utilization of light-weight materials for fuel economy and gas emissions reduction. I n addition, great efforts have been made on the NVH management to improve vehicle interior quietness and comfort. The car interior plays a significantly important role in aesthetics, sound, and vibration insulations, which can be economically and functionally improved by the use of textile materials [2]. In fact, nonwovens are widely used in the automotive industry due to their excellent characteristics, such as lightness of weight, sound

and vibration insulation, flexibility, versatility, easily tailored properties, moldability, recyclability, and low material and processing costs [3]. About 40 automotive parts or components are made of nonwovens in various forms, such as oil and air filters, headliners, insulator dashes/hoods, floor mats/carpets,doors/side trims, rear package trays, etc. [4].

Polyurethane (PU) foams are still the materials of choice for automotive seat cushion construction [5]. However,some deficiencies of PU foams have been recognized in relation to difficult recycling and toxic gas release during the manufacturing process. The recognition of such concerns has led to a new concept, namely, “textile foams” to replace PU foams with nonwoven textile structures. The advantages of nonwoven textile foams include reduced fogging and unwanted odors, environmentally-friendly laminating processes,surface material uniformity, the possibility of using reclaimed fibers, and recycling into reclaimed or recycled fibers [3].In this study, we attempted to understand nonwoven textile foams that are produced using the carding web formation process of hollow polyester fibers and low-melting binder fibers (bicomponent polyester fibers) to fully realize the greater potential for cushion materials to replace PU foams.These hollow fibers have a continuous hole running down the middle, which can provide greater bulkiness, compression resilience, and less weight with nonwoven fabrics in order to substitute PU foams in the automotive industry [6,7]. Effects of binder fibers and bonding processes, such as needle punching (NP) and/or thermal bonding (TB), are explored in terms of the physical and mechanical properties of the nonwovens through the understanding of the relationship between the bonding processes and nonwoven characteristics,such as tension, hardness, compression, and ball rebound resilience.

*Corresponding author: kkim@kitech.re.kr

DOI 10.1007/s12221-013-0639-9

640Fibers and Polymers 2013, Vol.14, No.4Ki-Young Kim et al.

Experimental

Materials

The commercial grade PET hollow fibers were used in this study for the main matrix fibers; the fibers were supplied by Woongjin Chemical, South Korea with 7 denier, 64 mm length, 4.1 g/den tenacity, and 29.7% hollowness. Two kinds of bicomponent polyester fibers were used for binder fibers, each containing heat fusible polymers at lower-melting temperatures. The binder fiber A was derived from co-polyester/polyester (PET) (sheath/core) staple fibers,obtained from Huvis, South Korea, with 4 denier and 51 mm length. The binder fiber B was derived from ELK ? fibers produced by Teijin, Japan, which are eccentric sheath/core type fibers of low-melting polyester elastomer and polyester polymers with 5 denier and 64 mm length. The characteristics and properties of the fibers are summarized in Table 1, and the cross sections of the fibers are shown in Figure 1.

For comparison, flexible molded polyurethane (PU) foams were taken from a driver’s seat in a Hyundai Grandeur TG model. The PU foam was found to have an open-cell microstructure with a density of 37.8 kg/m 3. The microstructure is shown in Figure 2, exhibiting an average cell diameter of 141 μm, strut thickness of 40 μm, and 650 pores per mm 2.Nonwoven Manufacture

Nonwovens were manufactured using a pilot scale nonwoven carding machine at the Korea Institute of Industrial Technology. The hollow fibers and the binder fibers were mixed at a weight ratio of 8:2, and then opened and carded

Table 1. Physical and mechanical properties of PET hollow fibers and binder fibers

Hollow PET

fibers

Binder fiber A Binder fiber B

Denier 7 denier 4 denier 5 denier Length 64 mm 51 mm 64 mm Tenacity 4.1 g/den 3.6 g/den 2.5 g/den Elongation 38.1 %60.8 %80.5 %Fiber diameter Inner : 35 μm Outer : 68 μm

26 μm 25 μm

Feature Hollowness : 29.7%Sheath/core (Low melting polyester)Eccentric sheath/

core (Low meting

polyester elastomer)

Figure 1. Cross-sections of fibers; (a) hollow PET fiber, (b) binder

fiber A, and (c) binder fiber B.

Figure 2. Microstructures of PU foams.

Effects of Binder Fibers and Bonding Processes on Nonwovens Fibers and Polymers 2013, Vol.14, No.4641

for web formation. The carded webs were laid by a cross lapper to produce nonwoven webs with an area density of 300 g/m 2 and a thickness of 10 mm. The resultant webs were post-processed and bonded only by a thermal bonding (TB)process, or needle punching and thermal bonding (NP+TB)combined processes. The webs were needle-punched at a punching rate of 170 stokes/min or thermally bonded by a double belt press at 170o C at a feeding speed of 2 m/min.Figure 3 and Table 2 show the manufacturing processes and sample identification in terms of binder fibers and bonding processes.

Testing Methods

A differential scanning calorimetric (DSC) study was carried out with a TA Instruments DSC Q20 at a heating rate of 5o C/min from room temperature to 300o C in nitrogen to characterize the melting behavior of hollow PET fibers and

binder fibers. Single fiber testing was performed through Favimat-Robot (Textechno, Germany) to analyze the tensile properties and linear density (fineness) of all types of fibers.The linear density was measured by the vibroscopic method,and the tensile tests were carried out using a gauge length of 20 mm at a crosshead speed of 10 mm/min with a pretension of 0.5 cN/dtex.

The thickness of nonwovens was measured at a compressive load of 0.5 gf/cm 2 using KES-FB3 (Kato Tech, Japan). The density was calculated based on the geometry of nonwovens and the area density. Air permeability of nonwovens was evaluated by TEXTEST FX 3300 at a differential pressure of 125 MPa (Air permeability can be expressed as the rate of air flow through a fixed fabric area per second).

For tensile tests, the manufactured nonwovens were cut into standard tensile specimens with a dimension of 50×250 mm (width×length) in accordance to KS M ISO 9073-3. The test gauge length was 200mm, and the tensile tests were performed with an Instron 3340 at a crosshead speed of 100 mm/min.For each specimen type, at least five specimens were tested in the machine direction (MD) and the cross direction (CD).Hardness measurement for nonwovens was carried out in accordance with KS M I SO 6672 with a universal testing machine (Tinus Olsen, England). The nonwovens were cut into a size of 50×50 mm (width×length). The five layers of nonwovens were laid up and compressed at a constant speed of 10 mm/min using a circular pressure foot with a 100 mm diameter. The hardness was determined as a measured load when the thickness was deformed to 30% of its original thickness. The hysteresis was calculated by equation (1)from the load-displacement curves during the hardness test.Hysterisis (%) = (1)

where A loading is the area under the load-displacement curve on loading, and A unloading is the area under the load-displacement curve on unloading.

Compressive properties of nonwovens are evaluated by KES-FB3. The nonwoven was compressed by a 20 cm 2pressure foot at a compressive deformation rate of 20 μm/sec. Three parameters -linearity (LC), compressive energy (WC), and resilience (RC) - were calculated by equation (2)-(4) [8]. (2)(3)

(4)

where A is the compressive area (2 cm 2), F m is the maximum

compressive load, F denotes the force during loading, and F'denotes the force during unloading. E m is the extension at

A loading A unloading –A loading

--------------------------------------LC FdE /0.5E m F m ()

Em ∫

=WC 1A ---FdE 0

Em ∫=RC %()F'dE /FdE 0

∫E r Em ∫[]100×

=Figure 3. Schematic of manufacturing processes for nonwovens.Table 2. Manufacturing conditions of nonwovens

Sample

Binder fiber

Bonding process

Needle punching Thermal bonding

PU foam ---NW A (TB)Binder fiber

A -○NW A (NP+TB)○○

NWB (TB)Binder fiber

B -○NWB (NP+TB)○○

642Fibers and Polymers 2013, Vol.14, No.4Ki-Young Kim et al.

F m, and E r is the extension after the load is returned to zero.

Permanent shrinkage (PS) or compression sets for nonwovens

represent the degree of permanent deformation. The nonwovens

were cut to the size of 50×50mm (width×length), and the

five layers were stacked to satisfy the minimum thickness

requirement of 50 mm in accordance with KS M ISO 6672.

The original thickness (T) of the stacked sample was

measured first. The nonwoven was pressed to 50% of the

original thickness using a thick aluminum plate fixture, and

then placed in a convection oven at 70o C for 22 hours. The

aged samples were removed from the oven and placed at a

standard condition of 20o C and 56% RH after the removal

of the fixture for 30 minutes. The final thickness (T1) was

measured and the permanent shrinkage (PS) was calculated

by the following equation.

(5)

Ball rebound tests were carried out in accordance with KS

M ISO 8307. A 16.8 g steel ball with a 16 mm diameter was

dropped from a height of 516 mm onto five layered nonwovens.

The rebound height was measured and corresponded to ball

rebound resilience as a percentage of the original height.

Results and Discussion

Thermal Behavior and Tensile Properties of Fibers

Figure 4 presents the differential scanning calorimetric

(DSC) thermograms of all the fibers studied. The PET

hollow fiber has only a single sharp endothermic peak with a

peak melting temperature of 251o C and a specific heat (?H)

of 52 J/g. The binder A and B fibers show two characteristic

melting peaks. The binder fiber A has a small endothermic

peak around 73o C and a sharp endothermic peak at 247o C,

corresponding to the melting temperatures of copolyester

(sheath) and PET (core) polymers, respectively. The binder

fiber B has a small endothermic peak around 62o C and a

sharp endothermic peak at 250o C, corresponding to the

melting temperatures of the low-melting polyester elastomer

and the PET polymer, respectively. The lower peak temperatures

are a good indicator of the minimum thermal bonding

processing temperatures.

The tensile behavior of all the fibers studied is illustrated

in Figure 5. The tenacity-elongation curves show a similar

trend as curves consisting of elastic and plastic portions.

Elastic deformation takes place in the initial portion of the

tenacity-elongation curves, where the tenacity is linearly

proportional to the elongation and the linear relationship

refers to an elastic modulus. In the second portion, corresponding

to plastic deformation, the load gradually increases, and the

strain range to the ultimate strain is significantly larger than the elastic range. From these results, it is found that the binder B fibers are more flexible than the other fibers studied, showing that lower maximum tenacity and greater elongation are due to the characteristic of elastomers. The tenacity and elongation are listed in Table 1, demonstrating that the hollow fiber has the highest tenacity and smallest elongation among all types of fibers studied. The binder

PS%

()

T T1

–

------------100

Figure 4. DSC thermograms of fibers; (a) hollow PET fiber, (b)

binder fiber A, and (c) binder fiber B.

Effects of Binder Fibers and Bonding Processes on Nonwovens Fibers and Polymers 2013, Vol.14, No.4643

fiber B shows greater elongation with a lower tenacity than

the other fibers.

Nonwoven Morphology and Properties

Figure 6 shows the SEM micrographs to illustrate the surface morphology of the nonwovens with bonding structures between the hollow main fibers and the binder fibers. The larger diameter hollow fibers are randomly distributed, and the smaller diameter low-melting binder fibers fuse and flow over the hollow matrix fibers, leading to fiber conjunction and bonding at their crossover areas. It is also observed that the binder fiber B facilitates fusion and flow to form a larger bonding area than the binder fiber A does.

The area density, thickness, and air permeability of nonwovens are summarized in Table 3. The area density and thickness show around 5% and 15% variations from processing set values of 300 g/m 2 and 10 mm, respectively,due to unknown parameters such as fiber properties and

Figure 5. Tensile tenacity-elongation curves for PET hollow fibers and binder fibers.

Figure 6. SEM micrographs of nonwovens; (a) NW A (TB), (b) NW A (NP+TB), (c) NWB (TB), and (d) NWB (NP+TB).

Table 3. Physical and mechanical properties of PU foams and nonwovens

Area density (g/m 2)Thickness (mm)Density (kg/m 3)Air permeability (cm 3/cm 2/s)Hardness (N)Support factor Hysteresis (%)PU foam 340.09.037.889.820.1 2.837.9NW A (TB)314.911.028.6169.449.5 5.644.9NW A (NP+TB)315.78.636.7161.294.47.853.4NWB (TB)302.410.129.9178.838.811.040.3NWB (NP+TB)

316.4

9.0

35.2

161.0

76.0

14.8

46.4

644Fibers and Polymers 2013, Vol.14, No.4Ki-Young Kim et al.

manufacturing conditions. I n particular, the thicknesses of NW A (NP+TB) and NWB (NP+TB) nonwovens are slightly lower than the thermal only bonded nonwovens because the needle punching results in fiber entanglements through the thickness direction of the webs, leading to a denser and better consolidated fabric structure. The relationship between area density and air permeability in Table 3 demonstrates that the NW A (NP+TB) and NWB (NP+TB) nonwovens have slightly lower air permeability than the other nonwovens due to their denser structures. It is usually observed that air permeability increases nonlinearly as thickness and area density decrease and that the area density has a more significant influence on air permeability than either thickness or fiber size [9]. In comparison with the PU foam, the higher permeability and lightness of the nonwovens indicate superior seating comfort and lightness for seat cushioning materials. The effects of binder fibers and bonding processes on tensile properties of nonwovens are clearly demonstrated by the load-displacement curves, as shown in Figure 7. For the machine direction (MD), the nonwoven strength is irrelevant to the bonding process but is dependent on the type of binder

fibers. The nonwovens bonded by the binder fiber A show a higher tensile peak load than the nonwovens bonded by the binder fiber B due to the higher tenacity of the binder fiber A (see Table 1). However, the higher elongation of the nonwovens bonded by the binder fiber B is the result of the intrinsic property of elastomeric fibers and better bonding structures. In addition, the only thermal bonded nonwoven,NW A (TP), has a similar strength but lower elongation in comparison with the needle punched and thermal bonded nonwovens, NW A (NP+TP). The nonwovens with the binder fiber B also show the same results. The needle punched and thermal bonded nonwovens have a better tensile performance than the thermal only bonded nonwovens in terms of elongation. The higher elongation can be attributed to a better structural integrity through the combined needle punching and thermal bonding processes. The tensile peak load in the cross direction (CD) exhibits a lower value for all tested samples than in the MD direction. The significant drops of the peak load in the CD direction are in strong agreement with the results reported in the literature [10] due to more aligned fibers in the MD direction by the main cylinders and the workers in carding processes.

Hardness is the resistance of materials to deformation under an applied force, which is one of the most important test parameters to determine seating comfort or discomfort.the load-compressional ratio curves for the nonwovens in the hardness tests are shown in Figure 8. The typical curve of PU foams exhibits three distinct regions: linear elastic,plateau, and densification (hardening). The PU foam has a higher load than the nonwovens in the elastic region.However, the load reaches a plateau value while the load for the nonwovens sharply increases. Finally, the hardness of PU foam, measured by 70% indentation force deflection (70% IFD) at a compressional ratio of 70%, is lower than that of all the nonwovens, as shown in Table 3. The NWB

(TB) nonwoven shows the highest softness with the lowest

Figure 7. Tensile load-dislacement curves of nonwovens; (a)

machine direction and (b) cross direction.

Figure 8. Typical load-compressional ratio curves of PU foam and nonwovens during hardness tests.

Effects of Binder Fibers and Bonding Processes on Nonwovens Fibers and Polymers 2013, Vol.14, No.4645

maximum load due to its bulkiness and low stiffness and that the nonwoven is similar to the PU slab foam. I t is worth noting that the additional needle punching process increases hardness for nonwovens due to denser fabric structures and that the incorporation of elastomeric fibers into nonwovens increases the softness. Furthermore, a support factor or sag,defined by a ratio of 65% IFD to 25% IFD, is one of the most important characteristics of foams because it governs comfort and durability [11]. The support factor of the PU foam in Table 3 has a value of 2.8. The 2.8 or higher values are regarded as providing good comfort [12]. If the cushioning material has a higher initial collapse load (25% IFD), the support factor is likely to be low and the seat may be uncomfortable. The higher support factors for the nonwovens demonstrate the greater potential of comfort cushioning materials.

The permanent shrinkage (PS) indicates irreversible deflection after 22 hours exposure at 70o C. Table 4 shows that the binder fiber B improves the durability of nonwovens due to a lower permanent shrinkage for the NWB nonwovens than for the NW A nonwovens. The lower permanent shrinkage for the NWB nonwovens implies a higher flexibility and better thickness recovery after compressive deflection. With respect to the effects of bonding processes on the NWB nonwovens, NWB (NP+TB) shows a lower permanent shrinkage than NWB (TB). Although the NW A nonwovens reveal the contrary result that NW A (NP+TB) shows a higher permanent shrinkage than NW A (TB), it is believed that fiber entanglement and secure fiber bonding induced by needle punching will improve thickness recovery and resistance to compressive forces, which are significantly promoted by the elastomeric binder fiber B.

The compression behavior for the PU foam and the nonwovens is depicted in Figure 9 for KES-FB3 tests. Three parameters of compression - linearity (LC), energy (WC),and resilience (RC) - are tabulated in Table 4. The LC indicates a linear response in the load-displacement curves in compression. The nonwovens show lower LC and WC than those of the PU foam, indicating that the nonwovens are more compressible and flexible. The compression resilience is the ability to return to original thickness after compression.The nonwovens, except for NW A (NP+TB), are more resilient and dissipate more energy than the PU foam. The

resilient nonwovens can present better performances with seating comfort and softness for seating pads. The discernible effects of binder fibers on compressive properties of nonwovens cannot be observed among the same bonding processes.However, the only thermal bonded nonwovens, NW A (TB)and NWB (TB), have a larger RC than NW A (NP+TB) and NWB (NP+TB), which is contrary to a previous report [13].The needle punching bonding process for nonwovens results in better consolidated structures and more fiber entanglement,which can reduce the fiber-to-fiber slippage during compression and improve the compression resilience. Although the contrary results cannot be clearly verified in this study, a possible explanation may be associated with the collapsing of through-thickness oriented fibers induced by the needle punching process and then the loss in the recovery to original thickness after compression.

The test results for ball rebound tests are shown in Figure 10.

Table 4. Compressive properties by K ES-FB3 and permanent shrinkage (PS) of PU foams and nonwovens

WC (gf·cm/cm 2)RC (%)PS (%)PU foam 1.420.459.825.0NW A(TB)

1.011.370.140.9NW A (NP+TB)0.8 6.055.645.7NWB (TB)0.79.968.129.1NWB (NP+TB)

0.6

7.1

61.7

27.2

Figure 9. Typical compressive load-extension curves of PU foam

and nonwovens by KES-FB3.

Figure 10. Ball rebound height and resilience of PU foam and nonwovens.

646Fibers and Polymers 2013, Vol.14, No.4Ki-Young Kim et al.

The rebound resilience shows a similar trend to the compression resilience measured by KES-FB3. The potential energy of a ball is transferred into the cushioning materials upon impact. The energy is absorbed partially by the materials, and the remaining energy is transferred back to the ball rebound. The low rebound height indicates high energy absorption materials, and thus it shows a good correlation with compression resilience.

Conclusion

The mechanical and seating-comfort performance of textile nonwoven foams were evaluated through the assessment of tensile properties, hardness, compression properties, and ball rebound resilience with regard to effects of binder fibers and bonding processes. The experimental results showed that the bonding processes and the type of binder fibers significantly affected the mechanical properties of the nonwovens. The combined bonding process of the needle punching and thermal bonding processes significantly improved tensile elongation of nonwovens due to better structural integrity, compared with the thermal only bonded nonwovens. I n addition, the elastomeric characteristics of the binder fiber B increased the tensile elongation to 120% and 150% for the NWB (NP+TB) nonwoven in the machine and cross directions, respectively.

The hardness, support factor, and compressive and ball rebound resilience were found to be the most important test parameters to determine seating comfort, although the correlation between the cushioning characteristics and seat comfort was difficult to determine qualitatively because seat comfort was extensively dependent on occupant preferences.

I n comparison with the PU form, the nonwovens showed greater firmness and their higher support factors, ranging from 5.6 to 14.5, indicated improved seating performances, e.g. a high level of comfort. The consistent results of compressive and ball rebound resilience indicated that the nonwovens, except for NW A (NP+TB), are more resilient and comfortable with a better characteristic of air permeability (twice as high as for PU foam). It can be concluded that the present study successfully demonstrated the greater potential of the nonwovens for cushion seat materials and that their greater design flexibility would satisfy various performance requirements of the automotive industry.

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第一部分办公软件操作与应用一、高效应用办公软件 1.正确认识办公软件； 2.注意掌握贴近实践的办公软件技能； 3.了解新功能，提高工作效率。（一）Office办公软件组件熟练掌握办公软件，有利于提高各种文档、报表和报告处理能力。尤其是几种常用办公软件的综合应用，更加能够大大提高财会人员的工作效率。比如工资单的处理和发放、财务报告的编制与分析、大数据的动态分析等等。（二）Office的学习方法在学习Office办公软件过程中，一定要注意以软件应用过程为导向的学习方法。一味地死记硬背，不仅仅学习非常辛苦，而且容易遗忘；更主要的是：一旦软件版本升级，又需要从头学习。二、高效办公必须懂的Office十八般武艺 Office的功能很多，不同的组件又有许多特有的功能。首先我们从Word、Excel、PowerPoint 共有的功能说起。下面和大家介绍十八个知识和技巧，从文件管理、文字处理到图像设置，帮助大家快速提高日常工作效率。（一）Office文件管理在Office中，对于文件的管理，比如文档的新建、打开、保存、另存为以及打印、发布等相关操作，通过软件界面左上角带Office图标的圆形按钮可以轻松实现。常见快捷方式

案例演示1：文件的加密在文档管理工作中，有一些重要的、私密的数据，需要通过文件的加密，来防止信息的泄露和无关人员的修改。Office2007可以通过文件加密，限制文件的阅读和修改。步骤：Office→另存为→工具→常规选项案例演示2：文件的打印在打印窗口，不仅仅能够设置打印机、打印范围和打印内容等等；还可以通过打印机属性，设置打印方式和打印质量；通过打印预览查看打印效果。步骤：Office→打印（二）Office选项通过点击Office按钮可以选择设置系统选项。包括软件的界面显示、作者标注、内容校对、保存方式、信任中心以及高级设置。案例演示：将报表中零值显示为空

when,while,as的区别

一、根据从句动作的持续性来区分 1.“主短从长”型：即主句是一个短暂性的动作，而从句是一个持续性动作，此时三者都可用。如： Jim hurt his arm while [when, as] he was playing tennis. 吉姆打网球时把手臂扭了。 As [When, While] she was waiting for the train, she became very impatient. 她在等火车时，变得很不耐烦。注意：as用于引出一个持续性动词表示“在……期间”时，其谓语通常只能是那些含有动作和发展意味的动词，一般不能是那些不用于进行时态的动词(如be, seem, love, want, agree, see, know, have 等)，所以下面一句中的while不能换为as： A：I’m going to the post office. 我要去邮局。 B：While you are there, can you get me some stamps? 当你在邮局时，能帮我买几张邮票吗? 若主句与从句表示的是两个几乎同时发生的动作，含有类似汉语“刚要……就”“正要……却”的意思，英语一般要用as(也可用when)，且此时通常连用副词just。且此时，从句一般用进行时，主句用短暂性动词的一般时态。【注意与六区别】 I caught him just when [as] he was leaving the building. 他正要离开大楼的时候，我把他截住了。 Just as [when] the two men were leaving, a message arrived. 就在这两个人要离开的时候，突然有了消息。 2.“主长从长”型：即主句和从句为两个同时进行的动作或存在的状态，且强调主句动作或状态延续到从句所指的整个时间，此时通常要用while。如： I always listen to the radio while I’m driving. 我总是一边开车一边听收音机。 He didn’t ask me in; he kept me standing at the door while he read the me ssage. 他没有让我进去，他只顾看那张条子，让我站在门口等着。但是，若主句和从句所表示的两个同时进行的动作含有“一边……一边”之意时，则习惯上要用as。如： He swung his arms as he walked. 他走路时摆动着手臂。 I couldn’t remember a story to tell the children, so I made one up as I went along. 我想不出有什么故事可给孩子讲了，只好现编现讲。 3.“主长从短”型：即主句是一个持续性动作，而从句是一个短暂性动作，此时可以用a s或when，但不能用while。如：

进程同步与通信作业习题与答案

第三章一．选择题(50题) 1.以下_B__操作系统中的技术是用来解决进程同步的。 A.管道 B.管程 C.通道 2.以下_B__不是操作系统的进程通信手段。 A.管道 B.原语 C.套接字 D.文件映射 3.如果有3个进程共享同一程序段，而且每次最多允许两个进程进入该程序段，则信号量的初值应设置为_B__。 4.设有4个进程共享一个资源，如果每次只允许一个进程使用该资源，则用P、V操作管理时信号量S的可能取值是_C__。 ,2,1,0，-1 ,1,0，-1，-2 C. 1,0，-1，-2，-3 ,3，2,1,0 5.下面有关进程的描述，是正确的__A__。 A.进程执行的相对速度不能由进程自己来控制 B.进程利用信号量的P、V 操作可以交换大量的信息 C.并发进程在访问共享资源时，不可能出现与时间有关的错误、V操作不是原语操作 6.信号灯可以用来实现进程之间的_B__。 A.调度 B.同步与互斥 C.同步 D.互斥 7.对于两个并发进程都想进入临界区，设互斥信号量为S，若某时S=0，表示_B__。 A.没有进程进入临界区 B.有1个进程进入了临界区 C. 有2个进程进入了临界区 D. 有1个进程进入了临界区并且另一个进程正等待进入 8. 信箱通信是一种_B__方式 A.直接通信 B.间接通信 C.低级通信 D.信号量 9.以下关于临界区的说法，是正确的_C__。

A.对于临界区，最重要的是判断哪个进程先进入 B.若进程A已进入临界区，而进程B的优先级高于进程A，则进程B可以打断进程A而自己进入临界区 C. 信号量的初值非负，在其上只能做PV操作 D.两个互斥进程在临界区内，对共享变量的操作是相同的 10. 并发是指_C__。 A.可平行执行的进程 B.可先后执行的进程 C.可同时执行的进程 D.不可中断的进程 11. 临界区是_C__。 A.一个缓冲区 B.一段数据区 C.一段程序 D.栈 12．进程在处理机上执行，它们的关系是_C__。 A.进程之间无关，系统是封闭的 B.进程之间相互依赖相互制约 C.进程之间可能有关，也可能无关 D.以上都不对 13. 在消息缓冲通信中，消息队列是一种__A__资源。 A.临界 B.共享 C.永久 D.可剥夺 14. 以下关于P、V操作的描述正确的是__D_。 A.机器指令 B. 系统调用 C.高级通信原语 D.低级通信原语 15.当对信号量进行V源语操作之后，_C__。 A.当S＜0，进程继续执行 B.当S＞0，要唤醒一个就绪进程 C. 当S＜＝ 0，要唤醒一个阻塞进程 D. 当S＜＝0，要唤醒一个就绪 16.对临界区的正确论述是__D_。 A.临界区是指进程中用于实现进程互斥的那段代码 B. 临界区是指进程中用于实现进程同步的那段代码 C. 临界区是指进程中用于实现进程通信的那段代码 D. 临界区是指进程中访问临界资源的那段代码 17. __A__不是进程之间的通信方式。 A.过程调用 B.消息传递 C.共享存储器 D.信箱通信 18. 同步是指进程之间逻辑上的__A__关系。

进程间通信的四种方式

一、剪贴板 1、基础知识剪贴板实际上是系统维护管理的一块内存区域，当在一个进程中复制数据时，是将这个数据放到该块内存区域中，当在另一个进程中粘贴数据时，是从该内存区域中取出数据。 2、函数说明： (1)、BOOL OpenClipboard( ) CWnd类的OpenClipboard函数用于打开剪贴板。若打开剪贴板成功，则返回非0值。若其他程序或当前窗口已经打开了剪贴板，则该函数返回0值，表示打开失败。若某个程序已经打开了剪贴板，则其他应用程序将不能修改剪贴板，直到前者调用了CloseClipboard函数。 (2)、BOOL EmptyClipboard(void) EmptyClipboard函数将清空剪贴板，并释放剪贴板中数据的句柄，然后将剪贴板的所有权分配给当前打开剪贴板的窗口。 (3)、HANDLE SetClipboardData(UINT uFormat, HANDLE hMem) SetClipboardData函数是以指定的剪贴板格式向剪贴板上放置数据。uFormat指定剪贴板格式，这个格式可以是已注册的格式，或是任一种标准的剪贴板格式。CF_TEXT表示文本格式，表示每行数据以回车换行(0x0a0x0d)终止，空字符作为数据的结尾。hMem指定具有指定格式的数据的句柄。hMem参数可以是NULL，指示采用延迟提交技术，则该程序必须处理WM_RENDERFORMA T和WM_RENDERALLFORMATS消息。应用程序在调用SetClipboardData函数之后，就拥有了hMem参数所标识的数据对象，该应用程序可以读取该数据对象，但在应用程序调用CloseClipboard函数之前，它不能释放该对象的句柄，或者锁定这个句柄。若hMem标识了一个内存对象，那么这个对象必须是利用GMEM_MOVEABLE标志调用GlobalAlloc函数为其分配内存。注意：调用SetClipboardData函数的程序必须是剪贴板的拥有者，且在这之前已经打开了剪贴板。延迟提交技术：当一个提供数据的进程创建了剪贴板数据之后，直到其他进程获取剪贴板数据之前，这些数据都要占据内存空间。若在剪贴板上放置的数据过大，就会浪费内存空间，降低对资源的利用率。为了避免这种浪费，就可以采用延迟提交计数，也就是由数据提供进程先提供一个指定格式的空剪贴板数据块，即把SetClipboardData函数的hMem参数设置为NULL。当需要获取数据的进程想要从剪贴板上得到数据时，操作系统会向数据提供进程发送WM_RENDERFORMA T消息，而数据提供进程可以响应这个消息，并在此消息的响应函数中，再一次调用SetClipboardData函数，将实际的数据放到剪贴板上。当再次调用SetClipboardData函数时，就不再需要调用OpenClipboard函数，也不再需要调用EmptyClipboard函数。也就是说，为了提高资源利用率，避免浪费内存空间，可以采用延迟提交技术。第一次调用SetClipboardData函数时，将其hMem参数设置为NULL，在剪贴板上以指定的剪贴板格式放置一个空剪贴板数据块。然后直到有其他进程需要数据或自身进程需要终止运行时再次调用SetClipboardData函数，这时才真正提交数据。 (4)、HGLOBAL GlobalAlloc( UINT uFlags,SIZE_T dwBytes); GlobalAlloc函数从堆上分配指定数目的字节。uFlags是一个标记，用来指定分配内存的方式，uFlags为0，则该标记就是默认的GMEM_FIXED。dwBytes指定分配的字节数。

软件维护及使用管理规定

软件维护及使用管理规定文稿归稿存档编号：[KKUY-KKIO69-OTM243-OLUI129-G00I-FDQS58-

日常办公软件及特殊软件维护及使用管理办法 1、目的：为有效使用及管理计算机软件资源,并确保公司计算机软件的合法使用，避免人员因使用非法软件，影响公司声誉或造成计算机病毒侵害，影响日常工作正常进行，特制定本办法。 2、适用范围：本办法适用于本公司软件使用的相关信息作业管理。一、软件安装及使用 1.公司的各类计算机软件，应依据着作版权者为限，并统一由信息技术部负责安装保管，信息管理软件及其它专用软件，需填制《IT资源申请单》（见附表info- 03）进行申请，获准后方可安装。 2.严禁个人私自在公司计算机上安装未获授权、非授权公司使用或超过使用授权数量的软件，未经授权或同意,使用者不得擅自在计算机内安装任何软件或信息，经授权同意者始得于计算机内安装合法授权的软件或信息。 3.各部门软件分配使用后，保管人或使用人职务变动或离职时，应移交其保管或使用的软件，并办理交接。 4.禁止员工使用会干扰或破坏网络上其它使用者或节点的软件系统，此种干扰与破坏如散布计算机病毒、尝试侵入未经授权的计算机系统、或其它类似的情形者皆在禁止范围内。 5.网络上存取到的任何资源，若其拥有权属个人或非公司所有，除非已经正式开放或已获授权使用，否则禁止滥用或复制使用这些资源。 6.禁止员工使用非法软件,或私人拥有的计算机软件安装使用于公司计算机上，也不得将公司合法软件私自拷贝、借于他人或私自将软件带回家中，如因此触犯着作权，则该员工应负刑事及民事全部责任，各部门应妥善保管正版软件，防止软件授权外泄或被非法使用。二、软件的相关维护升级管理

while、when和as的用法区别

as when while 的区别和用法 as when while的用法一、as的意思是“正当……时候”,它既可表示一个具体的时间点，也可以表示一段时间。as可表示主句和从句的动作同时发生或同时持续，即“点点重合”“线线重合”；又可表示一个动作发生在另一个动作的持续过程中，即“点线重合”，但不能表示两个动作一前一后发生。如果主句和从句的谓语动词都表示持续性的动作，二者均可用进行时，也可以一个用进行时，一个用一般时或者都用一般时。 1、As I got on the bus，he got off. 我上车，他下车。（点点重合）两个动作都是非延续性的 2、He was writing as I was reading. 我看书时，他在写字。（线线重合）两个动作都是延续性的 3、The students were talking as the teacher came in. 老师进来时，学生们正在讲话。（点线重合）前一个动作是延续性的，而后一个动作时非延续性的二、while的意思是“在……同时（at the same time that )”“在……期间(for as long as, during the time that）”。从while的本身词义来看，它只能表示一段时间，不能表示具体的时间点。在时间上可以是“线线重合”或“点线重合”，但不能表示“点点重合”。例如： 1、He was watching TV while she was cooking. 她做饭时，他在看电视。（线线重合） 2、He was waiting for me while I was working. 我工作的时候，他正等着我。（线线重合） 3、He asked me a question while I was speaking. 我在讲话时，他问了我一个问题。（点线重合）

进程间通信方式比较

进程间的通信方式： 1.管道（pipe）及有名管道（named pipe）：管道可用于具有亲缘关系进程间的通信，有名管道除了具有管道所具有的功能外，它还允许无亲缘关系进程间的通信。 2.信号（signal）：信号是在软件层次上对中断机制的一种模拟，它是比较复杂的通信方式，用于通知进程有某事件发生，一个进程收到一个信号与处理器收到一个中断请求效果上可以说是一致得。 3.消息队列（message queue）：消息队列是消息的链接表，它克服了上两种通信方式中信号量有限的缺点，具有写权限得进程可以按照一定得规则向消息队列中添加新信息；对消息队列有读权限得进程则可以从消息队列中读取信息。消息缓冲通信技术是由Hansen首先提出的,其基本思想是:根据”生产者-消费者”原理,利用内存中公用消息缓冲区实现进程之间的信息交换. 内存中开辟了若干消息缓冲区,用以存放消息.每当一个进程向另一个进程发送消息时,便申请一个消息缓冲区,并把已准备好的消息送到缓冲区,然后把该消息缓冲区插入到接收进程的消息队列中,最后通知接收进程.接收进程收到发送里程发来的通知后,从本进程的消息队列中摘下一消息缓冲区,取出所需的信息,然后把消息缓冲区不定期给系统.系统负责管理公用消息缓冲区以及消息的传递. 一个进程可以给若干个进程发送消息,反之,一个进程可以接收不同进程发来的消息.显然,进程中关于消息队列的操作是临界区.当发送进程正往接收进程的消息队列中添加一条消息时,接收进程不能同时从该消息队列中到出消息:反之也一样. 消息缓冲区通信机制包含以下列内容:

(1) 消息缓冲区,这是一个由以下几项组成的数据结构: 1、消息长度 2、消息正文 3、发送者 4、消息队列指针（2）消息队列首指针m-q,一般保存在PCB中。（1）互斥信号量m-mutex,初值为1，用于互斥访问消息队列，在PCB中设置。（2）同步信号量m-syn,初值为0，用于消息计数，在PCB中设置。（3）发送消息原语send （4）接收消息原语receive(a) 4.共享内存（shared memory）：可以说这是最有用的进程间通信方式。它使得多个进程可以访问同一块内存空间，不同进程可以及时看到对方进程中对共享内存中数据得更新。这种方式需要依靠某种同步操作，如互斥锁和信号量等。这种通信模式需要解决两个问题：第一个问题是怎样提供共享内存；第二个是公共内存的互斥关系则是程序开发人员的责任。 5.信号量（semaphore）：主要作为进程之间及同一种进程的不同线程之间得同步和互斥手段。 6.套接字（socket）；这是一种更为一般得进程间通信机制，它可用于网络中不同机器之间的进程间通信，应用非常广泛。 https://www.sodocs.net/doc/2617497584.html,/eroswang/archive/2007/09/04/1772350.aspx linux下的进程间通信-详解

第七--when-while-as-区别及练习.

When while as区别一、根据从句动作的持续性来区分 1、“主短从长”型：即主句是一个短暂性动作，而从句是一个持续性动作，此时三者都可用。如： Jim hurt his arm while［when， as］ he was playing tennis. 吉姆打网球时把手臂扭伤了。 2、“主长从长”型：即主句和从句为两个同时进行的动作或存在的状态，且强调主句动作或状态延续到从句所指的整个时间，此时通常要用while。 I always listen to the radio while I’m driving. 我总是一边开车一边听收音机。 He didn’t ask me in; he kept me standing at the door while he read the message. 他没有让我进去，他只顾看那张条子，让我站在门口等着。但是，若主句和从句所表示的两个同时进行的动作含有“一边……一边”之意时，则习惯上要用as。如： He swung his arms as he walked. 他走路时摆动着手臂。 3、“主长从短”型：即主句是一个持续性动作，而从句是一个短暂性动作，此时可以用as 或when，但不能用while。如： It was raining hard when [as] we arrived. 我们到达时正下着大雨。二、根据主句与从句动作是否同时发生来区分 1、若主句与从句表示的是两个同时发生的短暂性动作，含有类似汉语“一……就”的意思，英语一般要用as (也可用when)。如： The ice cracked as [when] I stepped onto it. 我一踩冰就裂了。 2、若主句与从句表示的是两个几乎同时发生的短暂性动作，含有类似汉语“刚要……就”“正要……却”的意思，英语一般要用as(也可用when)，且此时通常连用副词just。如： I caught him just when [as] he was leaving the building. 他正要离开大楼的时候，我把他截住了。三、根据是否具有伴随变化来区分若要表示主句动作伴随从句动作同时发展变化，有类似汉语“随着”的意思，英语习惯上要用as，而不用when或while。如： The room grew colder as the fire burnt down. 随着炉火逐渐减弱，房间越来越冷。注：若不是引导从句，而是引出一个短语，则用with，不用as。如： With winter coming on, it’s time to buy warm clothes. 随着冬天到来，该买暖和衣裳了。四、根据从句动作的规律性来区分若暗示一种规律性，表示“每当……的时候”，英语一般要用when。如： It’s cold when it snows. 下雪时天冷。五、根据主从句动作的先后顺序来区分若主句与从句所表示的动作不是同时发生，而是有先后顺序时，一般要用when。

linux进程间通讯的几种方式的特点和优缺点

1. # 管道( pipe )：管道是一种半双工的通信方式，数据只能单向流动，而且只能在具有亲缘关系的进程间使用。进程的亲缘关系通常是指父子进程关系。 # 有名管道(named pipe) ：有名管道也是半双工的通信方式，但是它允许无亲缘关系进程间的通信。 # 信号量( semophore ) ：信号量是一个计数器，可以用来控制多个进程对共享资源的访问。它常作为一种锁机制，防止某进程正在访问共享资源时，其他进程也访问该资源。因此，主要作为进程间以及同一进程内不同线程之间的同步手段。 # 消息队列( message queue ) ：消息队列是由消息的链表，存放在内核中并由消息队列标识符标识。消息队列克服了信号传递信息少、管道只能承载无格式字节流以及缓冲区大小受限等缺点。 # 信号( sinal ) ：信号是一种比较复杂的通信方式，用于通知接收进程某个事件已经发生。#共享内存( shared memory)：共享内存就是映射一段能被其他进程所访问的内存，这段共享内存由一个进程创建，但多个进程都可以访问。共享内存是最快的IPC方式，它是针对其他进程间通信方式运行效率低而专门设计的。它往往与其他通信机制，如信号量，配合使用，来实现进程间的同步和通信。 # 套接字( socket ) ：套解口也是一种进程间通信机制，与其他通信机制不同的是，它可用于不同及其间的进程通信。管道的主要局限性正体现在它的特点上：只支持单向数据流；只能用于具有亲缘关系的进程之间；没有名字；管道的缓冲区是有限的（管道制存在于内存中，在管道创建时，为缓冲区分配一个页面大小）；管道所传送的是无格式字节流，这就要求管道的读出方和写入方必须事先约定好数据的格式，比如多少字节算作一个消息（或命令、或记录）等等； 2. 用于进程间通讯(IPC)的四种不同技术: 1. 消息传递(管道,FIFO,posix和system v消息队列) 2. 同步(互斥锁,条件变量,读写锁,文件和记录锁,Posix和System V信号灯) 3. 共享内存区(匿名共享内存区,有名Posix共享内存区,有名System V共享内存区) 4. 过程调用(Solaris门,Sun RPC) 消息队列和过程调用往往单独使用,也就是说它们通常提供了自己的同步机制.相反,共享内存区

Office-办公软件的应用及操作-

Office 办公软件应用及操作第一模块WORD 操作及应用第一部分WORD 基本认识一、WORD 是Office 办公软件组中专门针对于文字编辑、页面排版及打印输出的应用软件。二、WORD 启动（略）三、WORD 窗口的基本构成： 1、标题栏：每次启动WORD 后自动生成一个暂命名为“文档1” 的空白文档。 2、菜单栏：提供所有控制WORD 应用的操作指令。共九个菜单 3、工具栏：常用菜单选项的快捷图标。经常使用的工具栏有：常用/格式/ 绘图/表格和边框/符号等。（*可在工具栏任意位置处单击右键，打开或隐藏相应的工具栏） 4、标尺：用于标注编辑区页面尺寸及划分情况。（* 单击“视图” - “标尺”可直接显示或隐藏该标尺。 5、编辑区：WORD 文档页面编辑排版的主要页面。一般默认以A4 纸为标准大小，划分为文本区和页边区。文本区是WORD 文档主体内容编辑区域；页边区内可完成页面的“页眉和页脚”的编辑。（** 用户在页面编辑排版时，单击“文件” -“页面设置”：可对当前页面的纸型/方向以及页边距的范围等属性进行设定。排版时可使用标尺快速调整页面） 6．状态栏/滚动条、滚动按钮（略）

第二部分 WORD 文档的基本操作及文字编辑一、WORD 文档的基本操作： 1保存/另存为：新建立的文档（即从未存过盘的文档）可单击“文件” -“保存” / “另标题栏（窗口构成如下图所示）菜单栏滚动条/滚动按钮 ?采毎标尺编辑区口如中⑨ 五号?R I 1! - A A 罔=至苴；I 0 2 - IjCEOEClft 点/ ? 世衣」亠證|止冋p;: t （Q ） ilii 肅d ）哥口帕楸讪） LjJjJ 2 J I 节状态栏

When while as的区别和用法(综合整理)

When while as的区别和用法 when的用法当主句使用持续性动词时. Dave was eating,when the doorbell rang.门铃响时,大卫在吃饭. 2.一个动作紧接着另一个动作发生. When the lights went out, I lit some candles.灯灭了,我赶紧点上一些蜡烛. 3.谈论生命中的某一阶段,或过去的某段时间. His mother called him Robbie when he was a baby. 在他很小时,他妈妈叫他Robbin. 4.指"每一次" When I turn on the TV, smoke comes out the back. 每当我打开电视,就有烟从后面冒出. while/as 的用法从句多为进行时,而且为持续性动词. I'll look after the children while you are making dinner. 你做饭,我来照顾孩子. 注意事项: (1) “主短从长”型：主句表示的是一个短暂性动作，从句表示的是一个持续性动作，三者都可用： He fell asleep when [while, as] he was reading. 他看书时睡着了。 Jim hurt his arm while［when，as］he was playing tennis. 吉姆打网球时把手臂扭伤了。 As［When，While］she was waiting for the train，she became very impatient. 她在等火车时，变得很不耐烦。 (2) “主长从长”型：若主、从句表示两个同时进行的持续性动作，且强调主句表示的动作延续到从句所指的整个时间，通常要用while： Don’t talk while you’re eating. 吃饭时不要说话。 I kept silent while he was writing. 在他写的时候，我默不做声。但是，若主从句表示的两个同时进行的动作含有“一边…一边”之意思，通常用as：

when,while,as引导时间状语从句的区别

when，while，as引导时间状语从句的区别 when，while，as显然都可以引导时间状语从句，但用法区别非常大。一、when可以和延续性动词连用，也可以和短暂性动词连用；而while和as只能和延续性动词连用。 ①Why do you want a new job when youve got such a good one already？（get 为短暂性动词）你已经找到如此好的工作，为何还想再找新的？ ②Sorry，I was out when you called me．（call为短暂性动词）对不起，你打电话时我刚好外出了。 ③Strike while the iron is hot．（is为延续性动词，表示一种持续的状态）趁热打铁。 ④The students took notes as they listened．（listen为延续性动词）学生们边听课边做笔记。二、when从句的谓语动词可以在主句谓语动作之前、之后或同时发生；while 和as从句的谓语动作必须是和主句谓语动作同时发生。 1．从句动作在主句动作前发生，只用when。 ①When he had finished his homework，he took a short rest．（finished先发生）当他完成作业后，他休息了一会儿。 ②When I got to the airport，the guests had left．（got to后发生）当我赶到飞机场时，客人们已经离开了。 2．从句动作和主句动作同时发生，且从句动作为延续性动词时，when，while，as都可使用。 ①When ／While ／As we were dancing，a stranger came in．（dance为延续性动词）当我们跳舞时，一位陌生人走了进来。 ②When ／While ／As she was making a phonecall，I was writing a letter．（make为延续性动词）当她在打电话时，我正在写信。 3．当主句、从句动作同时进行，从句动作的时间概念淡化，而主要表示主句动作发生的背景或条件时，只能用as。这时，as常表示“随着……”；“一边……，一边……”之意。 ①As the time went on，the weather got worse．（as表示“随着……”之意） ②The atmosphere gets thinner and thinner as the height increases．随着高度的增加，大气越来越稀薄。 ③As years go by，China is getting stronger and richer．随着时间一年一年过去，中国变得越来越富强了。 ④The little girls sang as they went．小姑娘们一边走，一边唱。 ⑤The sad mother sat on the roadside，shouting as she was crying．伤心的妈妈坐在路边，边哭边叫。 4．在将来时从句中，常用when，且从句须用一般时代替将来时。 ①You shall borrow the book when I have finished reading it．在我读完这本书后，你可以借阅。 ②When the manager comes here for a visit next week，Ill talk with him about this．下周，经理来这参观时，我会和他谈谈此事。三、when用于表示“一……就……”的句型中（指过去的事情）。 sb．had hardly（＝scarcely）done sth．when．．．＝Hardly ／Scarcely had sb．done sth．when．．．

Linux下的进程间通信-详解

Linux下的进程间通信-详解详细的讲述进程间通信在这里绝对是不可能的事情，而且笔者很难有信心说自己对这一部分内容的认识达到了什么样的地步，所以在这一节的开头首先向大家推荐著名作者Richard Stevens的著名作品：《Advanced Programming in the UNIX Environment》，它的中文译本《UNIX环境高级编程》已有机械工业出版社出版，原文精彩，译文同样地道，如果你的确对在Linux下编程有浓厚的兴趣，那么赶紧将这本书摆到你的书桌上或计算机旁边来。说这么多实在是难抑心中的景仰之情，言归正传，在这一节里，我们将介绍进程间通信最最初步和最最简单的一些知识和概念。首先，进程间通信至少可以通过传送打开文件来实现，不同的进程通过一个或多个文件来传递信息，事实上，在很多应用系统里，都使用了这种方法。但一般说来，进程间通信（IPC：InterProcess Communication）不包括这种似乎比较低级的通信方法。Unix系统中实现进程间通信的方法很多，而且不幸的是，极少方法能在所有的Unix系统中进行移植（唯一一种是半双工的管道，这也是最原始的一种通信方式）。而Linux作为一种新兴的操作系统，几乎支持所有的Unix下常用的进程间通信方法：管道、消息队列、共享内存、信号量、套接口等等。下面我们将逐一介绍。 2.3.1 管道管道是进程间通信中最古老的方式，它包括无名管道和有名管道两种，前者用于父进程和子进程间的通信，后者用于运行于同一台机器上的任意两个进程间的通信。无名管道由pipe（）函数创建： #include int pipe(int filedis[2])；参数filedis返回两个文件描述符：filedes[0]为读而打开，filedes[1]为写而打开。filedes[1]的输出是filedes[0]的输入。下面的例子示范了如何在父进程和子进程间实现通信。 #define INPUT 0 #define OUTPUT 1 void main() { int file_descriptors[2]; /*定义子进程号 */ pid_t pid; char buf[256]; int returned_count; /*创建无名管道*/ pipe(file_descriptors); /*创建子进程*/ if((pid = fork()) == -1) { printf("Error in fork\n"); exit(1); } /*执行子进程*/ if(pid == 0) { printf("in the spawned (child) process...\n"); /*子进程向父进程写数据，关闭管道的读端*/ close(file_descriptors[INPUT]); write(file_descriptors[OUTPUT], "test data", strlen("test data"));

进程间的通信

# 管道( pipe )：管道是一种半双工的通信方式，数据只能单向流动，而且只能在具有亲缘关系的进程间使用。进程的亲缘关系通常是指父子进程关系。 # 有名管道(named pipe) ：有名管道也是半双工的通信方式，但是它允许无亲缘关系进程间的通信。 # 信号量( semophore ) ：信号量是一个计数器，可以用来控制多个进程对共享资源的访问。它常作为一种锁机制，防止某进程正在访问共享资源时，其他进程也访问该资源。因此，主要作为进程间以及同一进程内不同线程之间的同步手段。 # 消息队列( message queue ) ：消息队列是由消息的链表，存放在内核中并由消息队列标识符标识。消息队列克服了信号传递信息少、管道只能承载无格式字节流以及缓冲区大小受限等缺点。 # 信号( sinal ) ：信号是一种比较复杂的通信方式，用于通知接收进程某个事件已经发生。# 共享内存( shared memory ) ：共享内存就是映射一段能被其他进程所访问的内存，这段共享内存由一个进程创建，但多个进程都可以访问。共享内存是最快的IPC 方式，它是针对其他进程间通信方式运行效率低而专门设计的。它往往与其他通信机制，如信号两，配合使用，来实现进程间的同步和通信。 # 套接字( socket ) ：套接口也是一种进程间通信机制，与其他通信机制不同的是，它可用于不同及其间的进程通信。 windows进程通信的几种方式（转） 2008-10-13 16:47 1 文件映射文件映射(Memory-Mapped Files)能使进程把文件内容当作进程地址区间一块内存那样来对待。因此，进程不必使用文件I/O操作，只需简单的指针操作就可读取和修改文件的内容。 Win32 API允许多个进程访问同一文件映射对象，各个进程在它自己的地址空间里接收内存的指针。通过使用这些指针，不同进程就可以读或修改文件的内容，实现了对文件中数据的共享。应用程序有三种方法来使多个进程共享一个文件映射对象。 (1)继承：第一个进程建立文件映射对象，它的子进程继承该对象的句柄。 (2)命名文件映射：第一个进程在建立文件映射对象时可以给该对象指定一个名字(可与文件名不同)。第二个进程可通过这个名字打开此文件映射对象。另外，第一个进程也可以通过一些其它IPC机制(有名管道、邮件槽等)把名字传给第二个进程。 (3)句柄复制：第一个进程建立文件映射对象，然后通过其它IPC机制(有名管道、邮件槽等)把对象句柄传递给第二个进程。第二个进程复制该句柄就取得对该文件映射对象的访问权限。文件映射是在多个进程间共享数据的非常有效方法，有较好的安全性。但文件映射只能用于本地机器的进程之间，不能用于网络中，而开发者还必须控制进程间的同步。 2 共享内存 Win32 API中共享内存(Shared Memory)实际就是文件映射的一种特殊情况。进程在创建文件映射对象时用0xFFFFFFFF来代替文件句柄(HANDLE)，就表示了对应的文件映射对象是从操作系统页面文件访问内存，其它进程打开该文件映射

.软件使用教程

目录一．关于U盘的软件 (2) 1 .ATTO Disk Benchmark.(测试U盘读写速度) (2) 2. MyDiskTest（测试U盘是否为扩容盘） (5) 3 .USBcleaner(U盘杀毒软件) (7) 二.硬盘分区及数据恢复软件 (9) 1.diskgenius （硬盘分区及数据恢复软件） (9) 2. Acronis Disk Director Suite (简称为ADDS) （分区管理器，无损分区） (9) 3. EASYRECOVERY（硬盘数据恢复工具） (9) 三.Ghost （硬盘备份还原工具，常用于重装系统） (10) Ghost 系统重装 (10) 另附：用NT6 HDD Installer硬盘安装 (10) 四．驱动安装的软件 (12) 1.E驱动（驱动安装） (12) 2驱动精灵（驱动检测与安装） (13) 五.windows激活 (16) 1.小马激活 (16) 2. CW激活 (16) 六.C-cleaner （清理Windows 个人电脑） (17) 七.卸载软件 (18) 1.添加删除程序（XP下）\卸载更改程序（win7下）（系统自带） (18) 2.完美卸载（智能卸载） (19) 3. microsoft fix it (微软官方修复工具) (21) 八.一般软件 (22) 1.360安全卫士 (22) 2.汉王OCR（PDF转换） (23) 3. Foxit PDF Reader（PDF阅读器） (23) 4.winrar（压缩包管理器） (24) 5.directX ，.net framework 4.0 ，Microsoft Visual C++ (24) 九.一些小程序（都在附件里） (24) 1.独木成林Dll文件智能修复_1.1 (24) 2. PowerRMV文件强制删除工具 (24) 3瑞星注册表修复工具 (25) 4. Autoruns，gmer，Procmon，TCPView (26) 现在主要讲常用的软件和一些技术员维修时需要用到的软件，在此，只是简单的一些应用，有兴趣的话可以多深入了解一下。（现在的软件很多，很多不同的软件都有相同的功能，现在讲的软件都只有一例，有兴趣的