A surgical stapling device particularly suited for endoscopic procedures is described The device includes a handle assembly and an elongated body extending distally from the handle assembly The distal end of the elongated body is adapted to engage a disposable loading unit A control rod having a proximal end operatively connected to the handle assembly includes a distal end extending through the elongated body A control rod locking member is provided to prevent movement of the control rod until the disposable loading unit is fully secured to the elongated body of the stapling device

Surgical Stapling Apparatus

Most of the signal processing that we will study in this course involves local operations on a signal, namely transforming the signal by applying linear combinations of values in the neighborhood of each sample point. You are familiar with such operations from Calculus, namely, taking derivatives and you are also familiar with this from optics namely blurring a signal. We will be looking at sampled signals only. Let's start with a few basic examples. Local difference Suppose we have a 1D image and we take the local difference of intensities, DI(x) = 1 2 (I(x + 1) − I(x − 1)) which give a discrete approximation to a partial derivative. (We compute this for each x in the image.) What is the effect of such a transformation? One key idea is that such a derivative would be useful for marking positions where the intensity changes. Such a change is called an edge. It is important to detect edges in images because they often mark locations at which object properties change. These can include changes in illumination along a surface due to a shadow boundary, or a material (pigment) change, or a change in depth as when one object ends and another begins. The computational problem of finding intensity edges in images is called edge detection. We could look for positions at which DI(x) has a large negative or positive value. Large positive values indicate an edge that goes from low to high intensity, and large negative values indicate an edge that goes from high to low intensity. Example Suppose the image consists of a single (slightly sloped) edge:

http://ieeexplore.ieee.org/iel5/5/31307/01456462.pdf

Linear systems

Wide bandgap semiconductors show superior material properties enabling potential power device operation at higher temperatures, voltages, and switching speeds than current Si technology. As a result, a new generation of power devices is being developed for power converter applications in which traditional Si power devices show limited operation. The use of these new power semiconductor devices will allow both an important improvement in the performance of existing power converters and the development of new power converters, accounting for an increase in the efficiency of the electric energy transformations and a more rational use of the electric energy. At present, SiC and GaN are the more promising semiconductor materials for these new power devices as a consequence of their outstanding properties, commercial availability of starting material, and maturity of their technological processes. This paper presents a review of recent progresses in the development of SiC- and GaN-based power semiconductor devices together with an overall view of the state of the art of this new device generation.

A Survey of Wide Bandgap Power Semiconductor Devices

Light-Emitting Diodes. (Monographs in Electrical and Electronic Engineering.) By A. A. Bergh and P. J. Dean. Pp. viii+591. (Clarendon: Oxford; Oxford University: London, 1976.) £22.

/pdf/light-emitting-diodes-ubzde6g9qc.pdf

Light-emitting diodes

A surgical stapling instrument (1) comprises a body portion (2, 3), a handle (4) and a staple fastening assembly (8). The staple fastening assembly (8) includes a curved cartridge (10), which comprises at least one curved open row of staples, and a curved anvil (22), which is adapted to cooperate with the cartridge (10) for forming the ends of the staples exiting from the cartridge (10). The staple fastening assembly (8) is adapted to allow unobstructed access towards the concave inner faces of the cartridge (10) and the anvil (22). The cartridge (10) can be moved towards the anvil (22) from a spaced position for positioning tissue therebetween to a closed position for clamping the tissue. Preferably, a knife is contained within the cartridge (10) and is positioned such that there is at least one row of staples on at least one side of the knife.

Surgical stapling instrument

Earlier planning and subsequent experience are described for the development of a 50-W, 300-Vdc power converter with power density targeted at 100 W/in3 and efficiency targeted at 95%. To achieve the desired power density, 3 - 5 MHz switching frequency was attempted, necessitating the choice of commercial eGaN® (enhancement-mode GaN FETs). Three-level isolated ZVS (Zero-Voltage-Switched) converter topologies were selected to best utilize with the 200-V ratings of the 5-MHz switches. A stacked gate driver is thus discussed for the three-level converter. For relative permeability below 50 needed by the magnetic components, magnetic powder has high core loss while gapped ferrites leads to high winding loss. Thus, a low-temperature process was developed to synthesize polymer-coated magnetic powder with permeability similar to that of commercial magnetic powder, but with loss approaching ferrites' loss. Constant-flux magnetic concept is described in companion papers as means to improve power density. Owing to the high reverse on-voltage of eGaN®, synchronous rectification is not a clear winner unless gate timing is precisely controlled. Experimental results at 3 MHz show that inverter's efficiency approaches 95% and dc-dc converter's efficiency approaches 85% at half the voltage rating of the eGaN® FETs.

Experience with 1 to 3 megahertz power conversion using eGaN FETs

Die attach by low-temperature sintering of nanoparticles of silver is an emerging lead-free joining solution for electronic packaging because of the high thermal/electrical conductivity and high reliability of silver. For bonding small chips, the attachment can be achieved by a simple heating profile under atmospheric pressure. However, for bonding chips with an area , an external pressure of a few MPa is reported necessary at the sintering temperature of ~ 250 °C. This hot-pressing process in excess of 200 °C can add significant complexity and costs to manufacturing and maintenance. In this paper, we conduct a fractional factorial design of experiments aimed at lowering the temperature at which pressure is required for the die-attach process. In particular, we examine the feasibility of applying pressure only during the drying stage of the process when the temperature is still at 180 °C. The experiments help to identify the importance and interaction of various processing parameters, such as pressure, temperature, and time, on the bonding strength and microstructure of sintered nanosilver joints. In addition, the positive effect of pressure applied during drying on the bonding quality is observed. With the results, a simpler process, consisting of pressure drying at 180 °C under 3 MPa pressure, followed by sintering at 275 °C under atmospheric pressure, is found to produce attachments with die-shear strengths in excess of 30 MPa.

Simplification of the Nanosilver Sintering Process for Large-Area Semiconductor Chip Bonding: Reduction of Hot-Pressing Temperature Below 200 $^{\circ}{\rm C}$

Low-temperature joining technology using nanosilver paste has been widely demonstrated for attaching power chips on silver or gold metallized substrates. In this paper, we investigate the processing conditions of nanosilver paste for bonding large-area chips on a plain copper surface. A double-print, low-pressure-assisted sintering process is developed for attaching the chips on copper. An evaluation criterion used in the process development is the bond strength of mechanical chips that are made of alumina and sintered on direct-bond-copper (DBC) substrates. The bond strength, measured by the die-shear test, is found to be in excess of 40 and 77 MPa at sintering pressures of 3 and 12 MPa, respectively, during sintering. Characterization of the bondline microstructure reveals a void-free sintered joint, the density of which increases, with increasing sintering pressure. Sintering in air causes partial oxidation of the copper surface, but the oxide can be easily removed by dipping in 1% hydrochloric acid solution. To evaluate the impact of the bonding and acid-cleaning process on device characteristics, a large-area insulated-gate-bipolar-transistor (IGBT) chip is bonded to DBC substrate and then wire-bonded for electrical testing. Test results shows that the die-attach process does not alter the IGBT performance.

Low-Pressure Joining of Large-Area Devices on Copper Using Nanosilver Paste

The transmission-line busbar filter is an innovative high-density electromagnetic interference (EMI) containment solution for power electronics systems. It uses the concept of the transmission-line EMI filter as a part of the power interconnection to eliminate the EMI noises in power converters. This paper presents a systematic study of the transmission-line busbar filter in a motor drive system, which includes its design, modeling, and improvement using a hybrid approach. The paper investigates the relationship between the busbar filter's in-circuit attenuation and its geometry, and then derives a general design guideline for the transmission-line busbar EMI filters. To improve the performance of the transmission-line busbar filter, the paper proposes a hybrid busbar filter combining a transmission-line busbar filter and a one-turn inductor. This improvement provides much higher attenuation than the traditional transmission-line busbar filters. These proposed concepts have been verified experimentally not only with small-signal measurement but also with in-circuit tests in a medium-power motor drive system.

Design of a Hybrid Busbar Filter Combining a Transmission-Line Busbar Filter and a One-Turn Inductor for DC-Fed Three-Phase Motor Drive Systems

The “constant-flux” concept is leveraged to achieve high magnetic-energy density, leading to inductor geometries with height significantly lower than that of conventional products. Techniques to shape the core and to distribute the winding turns to shape a desirable field profile are described for the two basic classes of magnetic geometries: those with the winding enclosed by the core and those with the core enclosed by the winding. A relatively constant flux distribution is advantageous not only from the density standpoint, but also from the thermal standpoint via the reduction of hot spots, and from the reliability standpoint via the suppression of flux crowding. In this journal paper on a constant-flux inductor (CFI) with enclosed winding, the foci are operating principle, dc analysis, and basic design procedure. Prototype cores and windings were routed from powder-iron disks and copper sheets, respectively. The design of CFI was validated by the assembled inductor prototype.

Khai D. T. Ngo

Papers

Experience with 1 to 3 megahertz power conversion using eGaN FETs

Simplification of the Nanosilver Sintering Process for Large-Area Semiconductor Chip Bonding: Reduction of Hot-Pressing Temperature Below 200 $^{\circ}{\rm C}$

Low-Pressure Joining of Large-Area Devices on Copper Using Nanosilver Paste

Design of a Hybrid Busbar Filter Combining a Transmission-Line Busbar Filter and a One-Turn Inductor for DC-Fed Three-Phase Motor Drive Systems

Inductor Geometry With Improved Energy Density