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Triggers And Views
... tạo trigger có dạng sau: CREATE TRIGGER trigger_name ON table_name or view_name FOR trigger_class and trigger_type(s) AS Transact-SQL statements Như tạo trigger ta phải rõ tạo trigger table trigger ... khác Columns_Updated() Xin xem thêm SQL Server Books Online để biết thêm chi tiết cách sử dụng Views Ðịnh nghĩa cách đơn giản view SQL Server tương tự Query Access database View xem table ảo ... data: Ta dùng view để làm cho users thấy data từ góc độ khác họ dùng nguồn data giống Ví dụ: Ta tạo views thông tin customer thể khác tùy login ID normal user hay manager • Export Import data: Ðôi...
Ngày tải lên: 25/08/2012, 09:00
Mechanisms and Mechanical Devices Sourcebook - Chapter 3
... APPLICATIONS Viscous liquid adhesives are used to glue fabrics and paper, apply paper labels, make cardboard and wooden boxes and shoes, and bind books Specially designed machines are required if ... 56 CUTTING MECHANISMS By pressing down on the foot pedal of this mechanism, the top knife and the clamp will be moved downward However, when the clamp presses on the material, both it and link ... would bend and jam Avoid these designs, if possible—Especially if automatic assembly methods will be employed A rotary screw-feed handles screws, headed pings, shouldered shafts, and similar...
Ngày tải lên: 22/10/2012, 14:26
Mechanisms and Mechanical Devices Sourcebook - Chapter 4
... 4, and T3/T4 = L3/L4 = 2/3, where T3 and T4 are the numbers of teeth on gears and T1 and T2 will denote the numbers of teeth on gears and 98 and S = ∆θ 3/θ30 Hence θ30(1 + S)L3 = 360º For S = and ... = r4 and r2 = r3, there is no “differential motion” and the output remains stationary Thus if one gear pair, say and 4, is made partly circular and partly noncircular, then where r2 = r3 and r1 ... intermittent mechanisms based on timing belts, pulleys, and linkages (see drawing) instead of the usual genevas or cams is capable of cyclic start -and- stop motions with smooth acceleration and deceleration...
Ngày tải lên: 22/10/2012, 14:26
Mechanisms and Mechanical Devices Sourcebook - Chapter 5
... Dynamic and static balancing is simplified when an expanding wheel is attached to a nonexpanding main wheel As a pulley, an expanding wheel can have a steel band fastened to only one section and ... 11:45 AM Page 134 TWELVE EXPANDING AND CONTRACTING DEVICES Parallel bars, telescoping slides, and other devices that can spark answers to many design problems Figs and Expanding grilles are often ... steel band, or rope around the drum is fastened to the driving and driven members; sprocket-wheels and chain can replace the drum and belt GEARS Fig Matching gear-segments Fig 10 Racks and coupled...
Ngày tải lên: 22/10/2012, 14:26
Mechanisms and Mechanical Devices Sourcebook - Chapter 6
... Bearing adjustment This screw arrangement is a handy way for providing bearing adjustment and overload protection Rapid and slow feed With left- and right-hand threads, slide motion with the nut locked ... bearings—such as the ball and roller bearings and of sliding bearings—which include sleeve and hydrostatic bearings Neither rolling nor sliding, flexures simply cross-suspend a part and flex to allow ... 0.4—A linear spring rate and high load resistance with small deflections For height to spring ratios between 0.8 and 1.0—An almost linear spring rate for fasteners and bearing and in stacks For rations...
Ngày tải lên: 22/10/2012, 14:26
Mechanisms and Mechanical Devices Sourcebook - Chapter 7
... 204 Fig Mechanisms for generating (A) modified cycloidal curves, and (B) basic cycloidal curves true cycloidal This is done by a second steel-band arrangement As carriage I moves, bands and cause ... equations of motion Fig A standard differential winch consists of two drums, D1 and D , and a cable or chain which is anchored on both ends and wound clockwise around one drum and counterclockwise around ... ROLLER CHAINS AND THEIR ADAPTATIONS Various roller, side-plate and pin configurations for power transmissions, conveying, and elevating STANDARD ROLLER CHAIN—FOR POWER TRANSMISSION AND CONVEYING...
Ngày tải lên: 22/10/2012, 14:26
Mechanisms and Mechanical Devices Sourcebook - Chapter 8
... power losses in the gears and bearings and from windage and churning of lubricant gear power: A gear’s load and speed capacity, determined by gear dimensions and type Helical and helical-type gears ... motor comparable in size and power to those used in standard reel-to-reel recorders, and a large bi-peripheral flywheel and sturdy capstan that reduces wow and flutter and drives the tape A patent ... manufacturing and alignment and (2) thermal and vibrational changes in the sizes and positions of the meshing components One of the benefits is a reduction of gear-toothcontact noise and vibration...
Ngày tải lên: 22/10/2012, 14:26
Mechanisms and Mechanical Devices Sourcebook - Chapter 9
... bi-directional slip and independent torque capacities for the two directions of rotation It requires two springs, one right-handed and one left-handed, for coupling the input, intermediate and output ... faster Edges of the clutch bands carry the entire load, and there is also a compound action of one band upon another As the torque builds up, each band pushes down on the band beneath it, so each ... requirements of MIL-E-5400, class and MILK-3926 specifications Applications were seen in counter and reset switches and controls for machines and machine tools, radar systems, and precision potentiometers...
Ngày tải lên: 22/10/2012, 14:26
Mechanisms and Mechanical Devices Sourcebook - Chapter 10
... clutch plates, gear fingers, and pinned members form the basis of these ingenious mechanisms Mechanical stops are often required in automatic machinery and servomechanisms to limit shaft rotation ... between the pin and the rotating finger must be shorter than the thread pitch so the pin can clear the finger on the first reverse-turn The rubber ring and grommet lessen the impact and provide a ... between the indicator and the actuating drive However, the force amplification between the indicator and the drive is rel- 349 Sclater Chapter 10 5/3/01 1:07 PM Page 350 Speed and Tension Control...
Ngày tải lên: 22/10/2012, 14:26
Mechanisms and Mechanical Devices Sourcebook - Chapter 11
... completely encased and cannot expand beyond its original diameter The standard pump is made of bronze and will handle volumes to 15 gpm The Squeegee develops a vacuum of 25 in of mercury and will work ... sucking and pushing actions and are not churned or foamed 370 PUMPING ACTION is produced by the meshing of the idler and rotor teeth in this rotary pump The idler is pinmounted to the head and the ... single-gland type Automatic wear control compensates for normal wear and maintains volumetric efficiency This pump will handle to 300 gph without churning or foaming It needs no lubrication and operates...
Ngày tải lên: 22/10/2012, 14:26
Mechanisms and Mechanical Devices Sourcebook - Chapter 13
... opposite sense to ψ14, ψ13 and ψ12 This establishes points A′2, A′3 and A′4, but here A′3 and A′4 coincide because of symmetry of A3 and A4 about A0B0 Draw lines A1A′2 and A1A′4, and the perpendicular ... a2/a1 and the initial position of the gear set, defined by the initial positions of θ1 and θ2, designated as θ10 and θ20, respectively Typical B-curve shapes (Fig 4) include ovals, cusps, and loops ... to maximize snap-action Over-centering toggle mechanisms, as shown in Fig 1, are widely used in mechanical and electrical switches, latch mechanisms and mechanical overload controls These toggles...
Ngày tải lên: 22/10/2012, 14:26
Mechanisms and Mechanical Devices Sourcebook - Chapter 14
... elements and icons, and 2D drafting and detailing capability, which support design collaboration and compatibility among CAD, CAM, and computer-aided engineering (CAE) applications Designers and engineers ... materials 2D drawing and detailing software packages are based on ANSI, ISO, DIN, and JIS drafting standards In a 2D CAD drawing, an object must be described by multiple 2D views, generally three ... reveal profile and internal geometry from specific viewpoints Each view of the object is created independently from other views However, 2D views typically contain many visible and hidden lines,...
Ngày tải lên: 22/10/2012, 14:26
Mechanisms and Mechanical Devices Sourcebook - Chapter 15
... revised and edited the Second Edition of Mechanisms and Mechanical Devices Sourcebook after the death of Mr Chironis The late Nicholas P Chironis developed the concept for Mechanisms and Mechanical ... engineer in the military/aerospace industry and a Boston engineering consulting firm before changing his career path to writing and editing on electronics and electromechanical subjects He was a ... and newspapers on various topics in engineering and industrial marketing Mr Sclater holds degrees from Brown University and Northeastern University, and he has completed graduate courses in industrial...
Ngày tải lên: 22/10/2012, 14:26
Mechanisms and Mechanical Devices Sourcebook - Chapter 12
... left-handed threads, • An eye on a shank with external righthanded threads, and • A flanged collar with left-handed external threads to mate with the shank of the firstmentioned eye, and right-handed ... connectors In step 5, the handle is pushed upward an additional 15º, locking the handle cam and the slide In step 6, the handle is rotated an additional 30º, forcing the box and the mating spring-loaded ... the handle and retention cams as the box is moved rearward and downward 409 Sclater Chapter 12 5/3/01 1:24 PM Page 410 Perpendicular-Force Latch (continued ) dle has been installed on the handle...
Ngày tải lên: 22/10/2012, 14:26
Mechanisms and Mechanical Devices Sourcebook - Chapter 16
... angular-momentum-balanced, robot ball -and- cone ball -and- disk, and ball -and- screw bearings and roller belt belt -and- chain, variable speed cam for machine tools for tool-slide mechanism two-directional rack -and- gear Links ... adjustable ball, and belt general Graham electrically-coupled planetary ring, and roller, and two curve-slider differential fixed general robot disk adjustable and roller ball, and general planetary ... ring and slider, Jenson’s robot rocker arm and disk roller-dwell rotary, short-dwell rotary-to-reciprocating motion and dwell rotary pump rotating crank screw screw, double-handed sector, rack -and- gear...
Ngày tải lên: 22/10/2012, 14:27
Mechanisms and Mechanical Devices Sourcebook - Chapter 17
... machine design instructors at the college and vocational school level, amateur and professional inventors, and students of all of the engineering disciplines and physical sciences Last but not least, ... and chronometer, to the cotton gin, and airplane were invented by self-trained engineers, scientists, and technicians By themselves, many of the mechanisms and devices described in this book are ... Also, some material considered to be obsolete and unsuitable for new designs was deleted For example, clockwork mechanisms for timing, control, and display have almost universally been replaced...
Ngày tải lên: 22/10/2012, 14:27
Mechanisms and Mechanical Devices Sourcebook - Chapter 18
... Motors and Typical Associated Mechanisms Flexures Accurately Support Pivoting Mechanisms and Instruments Taut Bands and Leadscrew Provide Accurate Rotary Motion Air Spring Mechanisms Obtaining Variable ... and Decelerating Linear Strokes Linkages for Multiplying Short Motions Parallel-Link Mechanisms Stroke Multiplier Force and Stroke Multipliers Stroke-Amplifying Mechanisms Adjustable-Stroke Mechanisms ... Sclater FM 5/3/01 9:50 AM Page viii Geneva Mechanisms Modified Geneva Drives Indexing and Intermittent Mechanisms Rotary-to-Reciprocating Motion and Dwell Mechanisms Friction Devices for Intermittent...
Ngày tải lên: 22/10/2012, 14:27