metal antenna masts and supports

... O 3 and the metal base is sintered carbide or cermet. For PCD, the ceramic is based on SiC and the metal on Co. References Brookes, K. J. A (1992)World Directory and Handbook of Hardmetals and ... Standards Organisation. Schwarzkopf, P. and Keiffer, R. (1960) Cemented Carbides. New York: MacMillan. Shelton, P. W. and Wronski, A. S. (1987) Strength, toughness and stiffness of wrought and ... V and L are the maximum and minimum operators. The union and intersection of the membership of two fuzzy sets m S ˜ o (V) and m S ˜ h (V) at any cutting speed V are respectively defined as, and

Ngày tải lên: 21/07/2014, 17:20

... (with minor amounts of WC and Co), and are known as cermets Much more detailed data are available on the composition and properties of the K- and P-type carbides (and M-type as well – see ... alloys and large amounts of strain hardening. The titanium alloys (right-hand panel) are hexagonal close packed (h.c.p.) or mixtures of h.c.p. and body centred cubic. Their initial yield and strain ... centred and body centred cubic materials. Further elementary reading on metal alloys, their mechanical properties and uses can be found in Rollason (1973), Cottrell (1975) and Ashby and Jones

Ngày tải lên: 21/07/2014, 17:20

... to x, y and z, and equation (A2.23) are substituted into I e (T) of equation A2.19. The variation of I e (T) with respect to T i , T j , T k and T l is established by differentiation and set ... asperity and flat obey... the left-hand part of Figure A3 .2, the asperity is shown flattened by a depth d1, and the flat by a depth d2, in accommodating the total overlap d and creating ... F-vector depend on the heat generation and loss quanti- ties q*, q and h, and the elements of [H] e depend mainly on the conduction and convec- tion terms of I e (T). Assembly of all the element

Ngày tải lên: 21/07/2014, 17:20

... example to F and G by HF and HG. Figure A1.7(b) is the velocity diagram. The velocities v F and v G of points F and G are determined from the rigid body rotation of the chip to be wOF and wOG, where ... suffixes i and j among the coefficients a ki and a lj . Thus equation (A1.22b) becomes s* kl = a ki a lj s ij (A1.22c) Furthermore, the repetition of k and l, between the left and right-hand sides ... suffixes, say m and n, for i and j: suffixes such as i and j, repeated on the same side of an equation, are called dummy suffixes and are said to be interchangeable. Suffixes such as k and l are called

Ngày tải lên: 21/07/2014, 17:20

... for Standardization International Standard (1995) ISO 5608: Turning and Copying Tool Holders and Cartridges for Indexable Inserts – Designation Geneva: International Organization for Standardization ... workpieces, predicted for different speeds and feeds Under the constraint of maximum wear land length of 0.2 mm and shortest cutting time, a cutting speed of 130 m/min and a feed of 0.225 mm would be chosen ... NN Qv, NN Blum and Inasaki (1990) Chen et al (1990) Dornfeld (1990) Moriwaki and Tobita (1990) Rangwala and Dornfeld (1990) Koren et al (1991) Chryssolouris et al (1992) Moriwaki and Mori (1993)

Ngày tải lên: 21/07/2014, 17:20

... notch and nose wear (VB, VN and VS) and operation variables to current forces The levels of VB, VN and VS, V, f and d were the inputs and Fd, Ff and Fc were outputs of the net; and ... shank height and width, and tool length 4 Holder type, i.e. approach angle, insert shape, size and thickness 5 Insert type, i.e. chip breaker type and carbide grade 6 Nose radius and insert tolerance ... holder no.7 and a coated insert of grade P10–P20 and nose radius 0.8 mm. When d a = 3 mm, the grade was unchanged but the tool holder and nose radius were altered to no. 3 and 1.2 mm; and the chip

Ngày tải lên: 21/07/2014, 17:20

... (9.14b) F 0 F h – F 1 where F l and F h are forces with a low and high expectation of fracture after N i impacts and F 0 , a and b are constants. Alternatively, and as considered further in Section ... quantitative and physical models, and used for a single purpose such as process understanding or to support process development, have been presented since the 1950s (e.g. Trigger and Chao, 1956). ... d(VB)/dt was estimated (from the stresses and temperatures; and for VB = 0.5 mm) to be 0.0065 mm/min at a cutting speed of 100 m/min and 0.024 mm/min at 200 m/min, and its change as VB increased could

Ngày tải lên: 21/07/2014, 17:20

... tool and type I and II tools with K = 1.2. The type I tool produces narrower plastic regions in the chip and workpiece, and less plastic deformation over the finished surface, than the type II and ... improvement and control Fig 9.1 Model-based systems for design and control of machining processes: (a) CAD assisted milling process simulator and planner (Spence and Altintas, 19 94) and ... angle. The x- and y-axes are, respectively, parallel and perpendicular to the cutting direction, and the z-axis is set along the major cutting edge. The tool is assumed to be stationary and rigid,

Ngày tải lên: 21/07/2014, 17:20

... for the less, and 10.0 for the more, ductile material, and V the cutting speed in mm/s. Friction between the chip and the tool is modelled according to equation (2.24c), with m and m both equal ... and Ortiz, 1995; Marusich, 1999); and the importance of fracture in concentrating shear is more strongly argued by some (Vyas and Shaw, 1999). Although the relative importance of frac- ture and ... listed in Table 8.1. They are identified as P (plain), X and Y (the steels with MnS added) and L (the steel with MnS and Pb). The steels X and Y differ in the size of their MnS inclusions: Table

Ngày tải lên: 21/07/2014, 17:20

... (Pentium II, 400 MHz CPU) and an assemblage of 390 nodes and 780 triangular elements. However, a pre- processor to prepare the finite element assemblage and a post-processor to handle a large amount ... extrapolation of these, and other power law equations, to strains much greater than 1... m/min: (a) and (c) as in Figures 8.1 and 8 .2 but (b) distribution of γm and hydrostatic pressure ... carbide tool with a zero rake angle and dry cutting. Figure 7.14 shows the predicted chip shape and nodal displacement vectors. Material separation at the tool tip and chip curl are successfully simulated.

Ngày tải lên: 21/07/2014, 17:20

... (6.26a) and (6.26b) are used to obtain a e and h′ c in terms of h c ; A sh is then obtained from h′ c , tool geometry and feed and depth of cut, from equation (6.41), using Tables 6.1 and 6.2 ... nodes, (x i ,y i ) for node i and simi- larly for j and k. The external loadings cause x and y displacements of the nodes, (u x,i ,u y,i ) at i and similarly at j and k. The adjacent elements ... Sections 6.2 and 6.3 established some of the difficulties and issues in analysing even steady-state and plane strain chip formation. The finite element method is a natural tool for handling the

Ngày tải lên: 21/07/2014, 17:20

... where A fc and A uc are, respectively, the cross-sectional areas of the formed and uncut chip; and A fc must be measured (for example by weighing a length of chip and dividing by the length and the ... to the cutting velocity. The directions and size of the feed and depth of cut are marked. Points such as 1 and 2 lie on the major cutting edge; and 3 and 4 on the tool nose radius or the minor ... used for both feed and uncut chip thickness, and depth of cut is used for both depth of cut and cutting edge engagement length. This section is the main part in which feed and depth of cut are

Ngày tải lên: 21/07/2014, 17:20

... basic properties and uses in detecting tool wear and chipping have been the subject of numerous investigations, for example Iwata and Moriwaki (1977), Kakino (1984) and Diei and Dornfeld (1987). ... boundaries between the primary shear zone and the work and chip and between the secondary shear zone and the chip are slip-lines. Figure 6.1 sketches slip-lines OA, A′D and DB that might be such boundaries. ... intersecting at the point 2 and labelled a and b, and an element of the slip-line field mesh labelled EFGH (with the shear stress k and hydrostatic pressure p acting on it); and it draws attention

Ngày tải lên: 21/07/2014, 17:20

... of, and Chapters and with the development and application of, finite element methods in machining analysis Chapter is concerned with embedding process understanding into process control and optimization ... 1.13 A traditional – column and knee – design and (right and below) partly-built and complete views of a modern (bed) design of milling machine In Figures 1.16(a) and (b) the capacity of a milling ... organizational gains of cell-oriented and FMS organization bring real benefit 1.4.3 Milling and drilling times and costs Equations (1.7) and (1.8) for machining time and cost of a turning operation...

Ngày tải lên: 17/12/2013, 11:15

... 34.18) The sand may be natural, synthetic, or an artificially blended material Molds The two common types of sand molds are the dry sand mold and the green sand mold In the dry sand mold, the ... prior to closing and pouring, while the green sand mold is used without any preliminary drying Because the dry sand mold is more firm and resistant to collapse than the green sand mold, core pieces ... as follows: Sand Centrifugal Permanent Die Plaster-mold Investment Sand Casting 441 Sand casting consists basically of pouring molten metal into appropriate cavities formed in a sand mold (Fig...

Ngày tải lên: 17/12/2013, 14:15

... switchgear and controlgear for alternating current of rated voltages above k v and up to and including 52 k v for indoor and outdoor installation, and for service frequencies up to and including ... contained in metal-enclosed switchgear and controlgear are to be designed and tested in accordance with their various relevant standards This standard supplements the standards for the individual components ... voltages, rated short-time withstand currents, rated peak withstand currents and rated normal currentsmetal-enclosed switchgear and controlgearreference is of made to I E C 56 and to I E C 129 -| | |...

Ngày tải lên: 25/12/2013, 10:57

... were : for Zn(II)–CeMT1 and Cd(II)–CeMT1 and : for Zn(II)– and Cd(II)–CeMT2, Zn(II)– and Cd(II)–CtCeMT1 and Zn(II)– and Cd(II)– CtCeMT2 Additionally, Zn(II)–DHisCeMT2 and Cd(II)– NtCeMT1 were ... Call2 and CalliCu, Callinectes sapidus, 1, and Cu isoforms (Uniprot accession numbers Q548Y3, Q548Y2 and Q9U620, respectively); Scy1 and Scy2, Scylla serrata isoforms and (Uniprot P02805 and P02806); ... CeMT1 and CeMT2 metallothioneins Fig Comparison between the CD spectra of recombinant CeMT1 and CeMT2 (black), NtCeMT1 and NtCeMT2 (red) and CtCeMT1 and CtCeMT2 (green) synthesized in Zn- and Cd-supplemented...

Ngày tải lên: 07/03/2014, 02:20

... in soil solution and bioavailability due to complexation with organic and inorganic soil colloides, sorption on oxides and clays and precipitation as carbonates, hydroxides and phosphates (Ruby ... amounts and modes of EDTA application on Pb, Zn and Cd uptake by test plant Brassica rapa We monitored the leaching of HMs and EDTA through the soil profile We also tested phytotoxicity and toxicity ... formation and other soil microorganisms Materials and methods Soil preparation and experimental set up Soil samples were collected from 0–30 cm surface layer at an industrial site of a former Pb and...

Ngày tải lên: 16/03/2014, 00:07

... Edition Elliot, R S., Antenna Theory and Design, Revised Edition Elliot, R S., Electromagnetics: History Theory, and Applications Felsen, L B., and Marcuvitz, N., Radiation and Scattering of Waves ... conformal antennas, as well as hands-on information necessary for the analysis and design of conformal antenna arrays Graphical illustrations are used extensively, both for calculated and measured ... that the book will become a useful tool for the practicing antenna and systems engineer in understanding and working with these interesting antennas Each chapter starts with some introductory material,...

Ngày tải lên: 17/03/2014, 13:45