定价： 1333元 / 折扣价： 1134 元 加购物车

定价： 515元 / 折扣价： 438 元 加购物车

This specification covers electrically insulating, unbleached sulfate paper and paperboard used as layer insulation in coils, transformers, and other similar apparatus. The materials may also be used as turn insulation, slot liners, wedges, phase insulation, and separator papers in stranded wire/cable constructions. This specification does not include tissue for manufacture of capacitors. Other commonly used terms for the materials include soft coil wrap, dense coil wrap, kraft coil insulation, dry-finished kraft, and water-finished kraft. The materials covered in this specification are classified into four types according to density range and nominal thickness and should conform to the required values of ash content, alcohol-soluble material content, aqueous extract conductivity, water-soluble chloride content, fiber composition, moisture content, hydrogen ion concentration, pH, tensile strength, dielectric breakdown voltage, and conducting paths.1.1 This specification covers electrical grade unsized, unbleached sulfate paper and paperboard for use as layer insulation in coils, transformers, and similar apparatus. Other applications include, but are not limited to, turn insulation, slot liners, wedges, phase insulation, and separator papers in stranded wire/cable constructions. Tissue for the manufacture of capacitors is not included in this specification. Other commonly used designations include:1.1.1 Soft Coil Wrap,1.1.2 Dense Coil Wrap,1.1.3 Kraft Coil Insulation,1.1.4 Dry-Finished Kraft, and1.1.5 Water-Finished Kraft.1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.1.3 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 515元 / 折扣价： 438 元 加购物车

1.1 This test method covers the radial sectioning technique 2,3,4 for measurement of the thickness of thin surface layers, made by a wide variety of processes, on metals, alloys, carbides, and oxides. 1.2 This test method is applicable to measurement of a wide variety of surface layer types where the interface between the layer and substrate is discernible by natural color or reflectivity differences or by means of color or reflectivity differences due to etching or staining. 1.3 This test method does not pertain to layer thickness measurements made by analysis of compositional variations. 1.4 This test method deals only with the recommended test method and nothing in it should be construed as defining or establishing limits of acceptability for any coating method. 1.5 The measurement values stated are in the metric system, as defined in Standard E380. 1.6 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety problems associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific precautionary statements, see Section 7.

定价： 0元 / 折扣价： 0 元

1.1 This provisional specification defines the Open Systems Interconnection (ISO7498 : 1984) Layer 2 data link layer for dedicated short-range communication (DSRC) equipment operating in half-duplex mode.1.1.1 This provisional specification defines the Data Link Layer irrespective of the physical medium to be used. However, it is expected that the standard will be used in accordance with a three layer stack as defined by Subcommittee E17.51 and IEEE P1455 and illustrated in . A critical implication of the use of the Data Link Layer standard with PS 111 is the assumption that the data rate will be 500 Kbps on both the uplink and downlink.1.1.2 This provisional specification specifies dedicated short range communications between fixed equipment at the roadside, called a beacon or Road Side Equipment (RSE) and Mobile Equipment in vehicles, called a Transponder or On-Board Equipment (OBE). This standard does not address vehicle-to-vehicle communication or communication between different instances of RSE.1.1.3 This provisional specification adheres to the general DSRC architecture in which the RSE controls the medium, allocating its use to OBEs within range of the RSE.1.1.4 This provisional specification supports a variety of RSE configurations. It supports configurations where one RSE communicates with one OBE, as well as configurations where one RSE can communicate with several OBEs. It does not define any specific configuration or layout of the communication zone.1.1.5 This provisional specification does not define to what extent different instances of RSE, operating in the vicinity of each other, need to be synchronised with each other.1.1.6 This provisional specification defines parameters to be used in negotiation procedures taking place between RSE and OBE.1.1.7 This provisional specification defines the following:Medium access control (MAC) procedures for the shared physical medium,Addressing rules and conventions,Data flow control procedures,Acknowledgement procedures,Error control procedures,Services provided to data link user(s), andFragmentation.1.1.8 There are two primary MAC modes, synchronous and asynchronous. Both modes support time-division multiple access half-duplex communications combined with a slotted aloha protocol for activation. The synchronous mode is characterized by a contiguous set of slots which is transmitted continuously and has fixed polling, data communications and activation phases. The asynchronous mode can vary the transmission of polling sequences, activation attempts or data communications.1.1.9 This provisional specification assumes that each RSE covers a limited part of the road (the communication zone) and that the OBE communicates with the RSE while passing through the communication zone.1.1.10 This provisional specification specifies the services required of the data link layer by the DSRC data link layer user, as viewed from the data link layer user, to allow a data link layer user entity to exchange packets with remote peer data link layer user entities. The services do not imply any particular implementation or any exposed interface.1.1.11 Not discussed in this provisional specification are signals that must be passed through the Data Link Layer from the Physical Layer to the Application Layer or vice versa in the OBE. These signals include indications of exceeding the wake-up threshold level (to control the OBE response in a small zone) and no carrier (to permit graceful shut down of the OBE if the OBE unexpectedly loses communications). It will be necessary to consider the implementation of these signals in OBE design.1.2 Overview1.2.1 All transmissions by either the RSE or OBE shall consist of a preamble and a frame. A preamble is an eight-bit sequence used for bit synchronization and is specified in Layer 1. A frame is a data link layer entity, which is the result of encapsulation of an application protocol data unit. The generic encapsulation process is shown in .1.2.2 An APDU is delivered from the application layer to the data link layer. If the APDU cannot be sent in a single transmission, then it is subdivided into multiple packets. Each packet is then converted into an LPDU by appending a byte count, fragmentation and logical link control and status field to the beginning of each packet. The frame is then formed by appending a link address field, and media access control field to the beginning and a error detection check field to the end of each LPDU. Each frame is then sent to the physical layer, which appends the preamble and then transmits the data.1.2.3 The frames can be transmitted in one of two modes: synchronous or asynchronous. In the synchronous mode, frames are transmitted in one of three types of slots: frame control message, message data or activation. The slots are combined to form a continuously repeated TDMA frame, as shown in . Each TDMA frame begins with a frame control message slot (FCMS). The FCMS only contains a frame control frame which is a broadcast message from the RSE indicating the number of slots, the type of each slot and the size of the slots that compose the rest of the TDMA frame. For example, in , the frame control frame defines a TDMA frame composed of three additional slots, two slots for data transmission and the other slot for activation. The message data slot (MDS) contains a data message frame transmitted over either the downlink to a specific OBE or uplink from a specific OBE. In addition, there is an acknowledgement transmitted immediately after the data message frame in the opposite direction. The activation slot (ACTS) consists of activation windows which are time periods when any OBE is allowed to transmit in contention with other OBEs in order to attempt to activate. It is not necessary to have an activation slot in a TDMA frame.1.2.4 Assuming link establishment requires the transmission of a beacon service table (BST) from the RSE and negotiation of link parameters using a vehicle service table (VST), provides an example of a full link negotiation followed by a read/write operation in synchronous mode. (Note that the full link negotiation can be shortened to reduce the number of TDMA frames needed to complete a transaction.) In TDMA Frame #1, the OBE receives a BST from the RSE and decides to activate. The activation is also transmitted in TDMA Frame #1. In TDMA Frame #2, the frame control frame designates a downlink message data slot to obtain the VST. After the OBE transmits the VST in TDMA Frame #2, the RSE commands the OBE to support a read in TDMA Frame #3. In TDMA Frame #4, the frame control frame designates an uplink message data slot to read the data. In TDMA Frame #5, the frame control frame designates a downlink message data slot to write data to the OBE. A corresponding acknowledgement is transmitted by the OBE.1.2.5 In the asynchronous mode, communications with an OBE is always initiated with a frame control frame which is regularly broadcast by the RSE. Immediately following the frame control frame are a series of activation windows. The timing and structure of the frame control frame and activation windows can be made common to both synchronous and asynchronous operations (to minimize the differences between the two modes). It is expected that the frame control frame and the activation windows will be transmitted (or time allocated) periodically so that the RSE can poll its read zone for OBEs. When an OBE successfully activates, the RSE discontinues transmissions of the frame control frame to establish private communications with the OBE. These communications can occur asynchronously, that is, without a TDMA frame dividing time into slots. In addition, the specific sequence of frames transmitted is dependent entirely on the application layer. Once the private communications is completed, the RSE would then continue to poll using the frame control frame and activation windows. Note that opportunities to transmit on the downlink and uplink in the asynchronous mode are defined by windows which provide constraints on the start and end times for any frame transmissions. An activation window is a special case of an uplink window.1.2.6 As above, assuming link establishment requires the transmission of a beacon service table (BST) from the RSE and negotiation of link parameters using a vehicle service table (VST), provides an example of a typical read/write operation in asynchronous operation.1.2.7 Like the synchronous mode, the OBE receives the BST from the RSE and attempts to activate. The activation frame is transmitted in activation windows that immediately follow the frame control frame. Once the activation is established, the RSE commands the OBE to transmit a VST and allocates an uplink window for the OBE to transmit the VST. After the VST is received, the RSE commands the OBE to support a read and allocates an uplink window for the OBE to transmit the read response. The OBE transmits the data. Then, the RSE writes data to the OBE and receives a reply that the write was successfully completed.Note 1Provisional Standards require only subcommittee consensus and are published for a limited time of two years. The provisional process was used because it is anticipated that the United States Department of Transportation will be referring to this provisional specification in their rule making.

定价： 0元 / 折扣价： 0 元

4.1 This classification is intended to encourage uniformity in reporting properties of MLS and Metal Layer gaskets, to provide a common language for communications between producers and users, and to guide engineers and designers in the application and construction of commercially available gaskets.(A) This classification may also be used to classify Single Layer Steel (SLS) Gaskets.(B) Refer to Specification A666 or Specification A109/A109M for Stainless Steel and Low Carbon Steel, respectively. Other metals not referenced in the table or not covered by Specification A666 or Specification A109/A109M must be defined by the producer/user (that is, H – High Temperature Alloy).(C) Refer to Practice D1418 for general information regarding rubber coating types and use Classification D2000 to define the physical properties of the rubber. This physical property information is typically specified on the gasket drawing or the customer specification, or both.(D) Coated side as specified on part drawing.4.2 Suffix Table 2 is provided to allow hardness designation for Active, Inactive, or Load Stoppers.4.2.1 If suffixes are not to be used, only the basic callout from Table 1 is required. If a suffix is used for 1 layer, it must be specified for all layers, even if a “0” is used. It cannot be assumed that hardnesses of like layers are the same; if used, all layers must be specified separately. The first layer specified must be indicated on the part drawing. To use a hardness call-out, at the end of the base callout leave a space followed by the “HR” suffix with a series of suffix numbers to specify the hardnesses for each layer.4.2.1.1 Example: ASTM F2325, A32ANBW11 HR252—Example from Table 1 modified to add hardness requirement for the three metal layers. Active layers 1 and 3 are designated to be the same, 1/4 hard steel. Stopper layer 2 is designated to be full hard steel.1.1 This classification covers a means for specifying Multi-Layer Steel (MLS) and other Metal Layer Gaskets for Transportation Applications by application and construction. These structures are composed of one or more steel or metal layers of material, which may have coatings or embossments. Commercial materials designated as composite or enveloped gaskets are excluded from this classification and are covered by Classification F868 and Practice F336, respectively.1.2 Since all of the properties that contribute to gasket performance are not included, use of this classification as a basis for selecting an MLS or Metal Layer gasket is limited.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 515元 / 折扣价： 438 元 加购物车

定价： 0元 / 折扣价： 0 元 加购物车

定价： 843元 / 折扣价： 717 元 加购物车

This specification describes a medium access control (MAC) and physical layer (PHY) specification for wireless connectivity using dedicated short-range communications (DSRC) services. This standard is based on and refers to IEEE Standards 802.11, Wireless LAN Medium Access Control and Physical Layer Specifications, and 802.11a, Wireless LAN Medium Access Control and Physical Layer Specifications High-Speed Physical Layer in the 5 GHz Band, with permission from the IEEE society. This specification is meant to be an extension of IEEE 802.11 technology into the high-speed vehicle environment. The difference between IEEE 802.11 and IEEE 802.11a operating parameters required to implement a mostly high-speed data transfer service in the 5.9-GHz Intelligent Transportation Systems Radio Service (ITS-RS) Band is explained. Potential operations within the Unlicensed National Information Infrastructure (UNII) Band are also addressed, as appropriate.1.1 This specification2 describes a medium access control (MAC) and physical layer (PHY) specification for wireless connectivity using dedicated short-range communications (DSRC) services. This standard is based on and refers to IEEE Standards 802.11, “Wireless LAN Medium Access Control and Physical Layer Specifications,” and 802.11a, “Wireless LAN Medium Access Control and Physical Layer Specifications High-Speed Physical Layer in the 5 GHz Band,” with permission from the IEEE Society. This specification is meant to be an extension of IEEE 802.11 technology into the high-speed vehicle environment. As presented here, this specification contains just enough information to explain the difference between IEEE 802.11 and IEEE 802.11a operating parameters required to implement a mostly high-speed data transfer service in the 5.9-GHz Intelligent Transportation Systems Radio Service (ITS-RS) band. Potential operations within the Unlicensed National Information Infrastructure (UNII) band are also addressed, as appropriate.1.2 Purpose—The purpose of this specification is to provide wireless communications over short distances between information sources and transactions stations on the roadside and mobile radio units, between mobile units, and between portable units and mobile units. The communications generally occur over line-of-sight distances of less than 1000 m between roadside units and mostly high-speed, but occasionally stopped and slow-moving, vehicles or between high-speed vehicles. This specification also offers regulatory bodies a means of standardizing access to the 5.9-GHz frequency band for the purpose of interoperable communications to and between vehicles at line-of-sight distances on the roadway.1.3 Specifically, this specification accomplishes the following:1.3.1 Describes the functions and services required by a DSRC and IEEE 802.11-compliant device to operate in a high-speed mobile environment.1.3.2 Refers to IEEE 802.11 MAC procedures.1.3.3 Defines the 5.9-GHz DSRC signaling technique and interface functions that are controlled by the IEEE 802.11 MAC.1.3.4 Permits the operation of a DSRC-conformant device within a DSRC communications zone that may coexist with multiple overlapping DSRC communication zones.1.3.5 Describes the requirements and procedures to provide privacy of user information being transferred over the wireless medium and authentication of the DSRC or IEEE 802.11-conformant devices.1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 843元 / 折扣价： 717 元 加购物车

5.1 TLC is an inexpensive and simple technique that could be used to complement other analytical techniques within a general analytical scheme related to forensic fiber examination.5.2 Consider the forensic analysis of fiber colorants using TLC for single fiber comparisons only when the sample size is adequate (that is, enough colorant can be extracted for analysis) and it is not possible to discriminate between the fibers of interest using other techniques, such as comparison microscopy and MSP. Larger fibrous units (for example, thread or tuft) can be treated as an individual sample if determined to be homogeneous. Do not treat fibers that cannot be directly related to each other as a collective sample for the purposes of TLC.5.3 The extraction procedures carried out prior to TLC analysis can provide useful information about dye classification. TLC can provide qualitative information about dye components. Similar colors made up of different dye components can be differentiated using this technique. The application of TLC may serve to discriminate between fibers or it may support the possibility of fibers sharing a common source.5.4 TLC can be prohibitively difficult or undesirable in some circumstances. Short lengths of fibers or pale-colored fibers can lack adequate amounts of colorant necessary to be examined by TLC. Dye extraction from some fibers can be impossible (2, 3). Some fiber types do not truly extract, but change or lose color. Reactive dyes are covalently bonded to the fiber and typically cannot be removed by conventional extraction methods, but can be released from cotton and wool by disrupting the fiber by enzymatic or chemical digestion, respectively (1). The desire to preserve evidence from deleterious change or for possible analysis by another examiner can preclude removing the color or employing a destructive method for analysis.1.1 This guide is intended as an overview of the Thin-Layer Chromatography (TLC) of fiber colorants (or individual dye components) present in dyed fibers. It is intended to be applied within the scope of a broader analytical scheme for the forensic analysis of fiber samples. TLC could provide information that cannot be obtained through other color analyses (such as microspectrophotometry (MSP)) (1).21.2 This standard is intended for use by competent forensic science practitioners with the requisite formal education, discipline-specific training (see Practice E2917), and demonstrated proficiency to perform forensic casework (see Practice E3255).1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 590元 / 折扣价： 502 元 加购物车

This specification covers manufacturing and joining requirements for peelable or skinned polyethylene (PE) pipe, which is PE pipe meeting the requirements of Specification D2513, with a peelable outer layer of polypropylene (PP). The peelable PP layer does not contribute to outside diameter and wall thickness used for pressure rating or tensile loading calculations.1.1 This standard specification covers manufacturing and joining requirements for peelable (skinned) polyethylene (PE) pipe, which is PE pipe meeting the requirements of Specification D2513, with a peelable outer layer of polypropylene (PP). These requirements are in addition to those in Specification D2513 for the PE pipe.1.2 The peelable PP layer does not contribute to outside diameter and wall thickness used for pressure rating or tensile loading calculations.1.3 The text of this standard references notes and footnotes which provide explanatory material. These notes and footnotes (excluding those in figures and tables) shall not be considered as requirements of the standard.1.4 Units—The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 515元 / 折扣价： 438 元 加购物车

定价： 515元 / 折扣价： 438 元 加购物车

定价： 515元 / 折扣价： 438 元 加购物车

4.1 The United Nations Committee of Experts on the Transport of Dangerous Goods in their recommended regulations place materials having a flash point below 23 °C (73.5 °F) in Packing Group II. However, if viscous substances such as paint and related coatings, adhesives, polishes, etc., meet certain requirements, they can be placed in Group III along with materials having a flash point between 23 °C and 60.5 °C (73.5 °F and 140 °F). One of the requirements is that less than 3 % of clear liquid separates from the bulk of the material when subjected to this test method.4.2 At the present time most international regulatory bodies such as the International Civil Aviation Organization (ICAO) and the International Maritime Organization (IMO) use the U.N. Recommendations. It is anticipated that most national transportation regulatory bodies will adopt the U.N. Recommendations as their regulations for control of transportation of hazardous materials. At present the United States permits the transshipment of hazardous materials through the United States to other countries under regulations of the IMO and ICAO.1.1 This test method covers the determination of the amount of liquid separated as an upper layer in a 24-h period from viscous solutions or dispersions that contain dispersed solids such as paints, enamels, pigmented lacquers, adhesives, polishes, and other similar materials.NOTE 1: The amount of clear liquid that separates during this test is one of the criteria in the United Nations Recommendations on the Transportation of Dangerous Goods2 for the placement of flammable viscous liquids into packing groups related to flash points (See 4.1).1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 515元 / 折扣价： 438 元 加购物车

定价： 515元 / 折扣价： 438 元 加购物车