are space time block codes really necessary

... for these stacks and compared their results The current-voltage (I-V) characteristics of the nanostack with in-plane area (A) of 0.25 µm2 (J2) at various temperatures, are presented in Fig The ... 10-3) and the related grating lengths are of the order of several millimeters To reduce the grating length, strong refractive index modulations (Δnmod > 10-2) are necessary Strong Δnmod can be obtained ... that are required for the channels A comparatively fast wet or dry etching rate of µm/min would still require up to several hours per wafer to achieve these depths The small surface areas that are...

Ngày tải lên: 27/06/2014, 01:20

... formulas and calculations quick and easy Examples are used throughout to make the formulas as easy as possible to understand and work, and often exact words are used rather than symbols This book is ... per foot, using the following data: Basic Formulas Bit cost (B) Rig cost (C,) Rotating time (T) Round trip time (T) (for depth-1 0,000ft) Footage per bit ( F ) c, 2500 = = $2500 = $900/hour = 65 ... bottomhole assembly (BHA) necessary for a desired weight on bit (WOB) Feet of drill pipe that can be used with a specific bottomhole assembly (BHA) Length of bottomhole assembly necessary for a desired...

Ngày tải lên: 02/04/2014, 16:04

... x i– and x i+ are the domain intervals of variable xi, xi ∈ Xi There are 2N + fuzzy regions quantifying the universe of discourse Xi The center points of each linguistic variable are (x – i ( ... reasons, researchers are seeking solutions to model the surface roughness in an online or in-process fashion ©2001 CRC Press LLC The studies of Martellotti [1941, 1945] are among the earliest ... five steps 16.2.2.1 Step 1: Divide the Input and Output Spaces into Fuzzy Regions [ ] Assume that the domain intervals of input variable xi are x i– , x i+ , and that the domain intervals of [y...

Ngày tải lên: 23/01/2014, 01:20

Ngày tải lên: 19/02/2014, 12:20

... accepted principles of international law Thus, the GOM OCS covers an area of over 600,000 square kilometers, a little less than the area of Texas and twice the size of Poland As Figs 2.2 and 2.3 show, ... follows: Mass and energy are conserved The qualities of matter and energy deteriorate (become less useful to us) over time Whatever happens1 to a chunk of matter with time, the first law above ... oil per day But, with time, Mother Nature imposes the ever more stringent daily withdrawal limits on our ATM cards Old and easy oil reservoirs are depleted, the new ones are less productive, and...

Ngày tải lên: 21/02/2014, 18:20

... rotational motion as it enters, or exit’s the workpiece   ‘Jobber drills’ are considered to be ‘standardised drills’ that are normally utilised for most drilling general operations, unless otherwise ... held in a spindle will have its rigidity decreased by the ‘square of the distance’ , namely, if a drill is twice as long it is four times less rigid ‘Web’ refers to the internal core of the drill ... thrust force occurs and an inefficient drilling action will result  ‘Split-point’ ground drills are sometimes referred to as ‘Multifacet drills’ NB  A cantilevered tool such as a boring bar has its...

Ngày tải lên: 21/06/2014, 21:20

... both Special-purpose and Multi-spindle drilling tooling, then 27 Short cycle times, are considered to be the quickest time that the part can be produced, under ‘standard’ machining conditions 28 ... counter-bored depth Counter-boring heads are employed to open-out existing holes (Fig 55a) The heads were in the past, often of a single insert design, but latterly, they are produced with multiple inserts ... purpose-designed and built tooling to amortised26 over the cost of the production period, • Short cycle times27 – when time is the ‘essence of importance’ in the production of the component, but it is not necessarily...

Ngày tải lên: 21/06/2014, 21:20

... to add spacers/shims to precisely control the boring bars overall length, this is particularly important when medium-to-long production batches are necessary, in order to minimise cycle time and ... needs to be carefully monitored and controlled It is usual practice to have a ro- 35 Asymmetric Drill Head design, refers to the fact that the cutting inserts are not only radially, but are angularly ... utilising cemented carbide tool shanks, is its greater brittleness when compared to steel, so careful tool design is necessary to minimise this problem ‘Compound’ boring bar tool shanks have been...

Ngày tải lên: 21/06/2014, 21:20

... motions in space, these are: backward/forward, upward/downward and leftward/rightward NB  Of some interest but in the main, to machine tool builders for the purposes of volumetric calibration, are the ... it are possible However, tool deflections are more difficult, if not impossible to completely eliminate, with these longer cantilevered tools Of note regarding overhanging tool deflections, are ... cutting inserts axially situated a little way in front of the other, while at the same time, the cartridges are radially adjusted enabling the front insert to cut a slightly smaller diameter to...

Ngày tải lên: 21/06/2014, 21:20

... tooling’ 51 The chip area (i.e illustrated in Fig 66b – right), has an effect on the load on the insert’s cutting edge, particularly when hard-part boring, although with small chip areas, this may ... reamers can be divided into several categories, these are: multi-point reamers with either a straight, or Morse taper55 shank, these reamers are usually either manufactured from: HSS, Tungsten ... ‘long-chipping’ workpiece materials Reamers with straight flutes are usually utilised to ream blind holes, but with the absence of chip space at the bottom, this means that swarf must be evacuated...

Ngày tải lên: 21/06/2014, 21:20

... operation There are a number of these pre- and post-drilling hole operations that require specific tooling to finish off the hole-making activities The most popular of these are briefly mentioned ... exhaustive account of the many often hybrid operations that are available to the potential designer, or machinist Countersinks There are several reasons why a countersink tool might be employed ... rather than to form it, via specially-modified tools that are fed to the other side of the part, then circular interpolation techniques are used to create the required back-face NB  With most of...

Ngày tải lên: 21/06/2014, 21:20

... engagement positioning relationships are depicted in Fig 84, indicating where the most favourable cutter/workpiece relationships are present Also in Fig 84, are depicted some unfavourable engagements ... of time engaged in the actual cut For example, in Fig 84g, a cutter has been positioned centrally over the workpiece, this produces the shortest possible time 17 ‘Location and restraint’ , are ... cross-sectional areas These high-insert density milling cutters, are usually recommended when machining high-temperature exotic alloys, or hard steels – where light chip loads are taken As a result...

Ngày tải lên: 21/06/2014, 21:20

Ngày tải lên: 21/06/2014, 21:20

... magnitude of 405 times to 148 nm The specific surface area has increased from 0.249 m2/gm for fresh fly ash to 25.53 m2/gm for fly ash ball milled up to 60 h The increase in surface area has been found ... with milling time (in hours) Table Surface energy and work of adhesion of fresh as well as ball milled fly ash Fly ash sample Fig Variation of Specific surface area of fly ash with milling time (in ... milling time Fig FTIR spectrum of fresh and ball milled fly ash at varying time, (A) Fresh Fly ash, (B) Ball milled for 20 h, (C) Ball milled for 40 h and (D) Ball milled for 60 h milling time is...

Ngày tải lên: 22/06/2014, 18:20

... to add spacers/shims to precisely control the boring bars overall length, this is particularly important when medium-to-long production batches are necessary, in order to minimise cycle time and ... both Special-purpose and Multi-spindle drilling tooling, then 27 Short cycle times, are considered to be the quickest time that the part can be produced, under ‘standard’ machining conditions 28 ... needs to be carefully monitored and controlled It is usual practice to have a ro- 35 Asymmetric Drill Head design, refers to the fact that the cutting inserts are not only radially, but are angularly...

Ngày tải lên: 27/06/2014, 14:20

... to add spacers/shims to precisely control the boring bars overall length, this is particularly important when medium-to-long production batches are necessary, in order to minimise cycle time and ... both Special-purpose and Multi-spindle drilling tooling, then 27 Short cycle times, are considered to be the quickest time that the part can be produced, under ‘standard’ machining conditions 28 ... needs to be carefully monitored and controlled It is usual practice to have a ro- 35 Asymmetric Drill Head design, refers to the fact that the cutting inserts are not only radially, but are angularly...

Ngày tải lên: 27/06/2014, 23:20

Ngày tải lên: 06/07/2014, 10:21

... rotational motion as it enters, or exit’s the workpiece   ‘Jobber drills’ are considered to be ‘standardised drills’ that are normally utilised for most drilling general operations, unless otherwise ... held in a spindle will have its rigidity decreased by the ‘square of the distance’ , namely, if a drill is twice as long it is four times less rigid ‘Web’ refers to the internal core of the drill ... thrust force occurs and an inefficient drilling action will result  ‘Split-point’ ground drills are sometimes referred to as ‘Multifacet drills’ NB  A cantilevered tool such as a boring bar has its...

Ngày tải lên: 05/08/2014, 20:22

... force and torque formulae derived in the work by Kaczmarek, are concerned with ‘so-called’ average twist drilling values These ‘averages’ are related to drill diameters between 15 to 35 mm, having ... geometries [After: Kaczmarek, 1976] Drilling and Associated Technologies 99 • Land, or margin – via a rubbing, or frictional ac- A = 2Az = szd = sd/2 = 2hzb tion NB  The latter two are relatively inefficient ... cross-sectional area of the undeformed chip at each of the twist drill’s cutting lips, can be shown by the following relationship: Az = szd/2 = sd/4 = hzb (mm2) Hence, the total transverse cross-sectional area...

Ngày tải lên: 05/08/2014, 20:22

... both Special-purpose and Multi-spindle drilling tooling, then 27 Short cycle times, are considered to be the quickest time that the part can be produced, under ‘standard’ machining conditions 28 ... needs to be carefully monitored and controlled It is usual practice to have a ro- 35 Asymmetric Drill Head design, refers to the fact that the cutting inserts are not only radially, but are angularly ... purpose-designed and built tooling to amortised26 over the cost of the production period, • Short cycle times27 – when time is the ‘essence of importance’ in the production of the component, but it is not necessarily...

Ngày tải lên: 05/08/2014, 20:22