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

A nanosilver-sintering-enabled die-bonding technique has been widely applied for attaching power semiconductor devices onto the surfaces of noble metals such as silver or gold. Recently, high bonding strength (> 35 MPa) of die attachment has been demonstrated by sintering on bare copper surface. In this work, the temperature cycling reliability of joints processed by nanosilver sintering on bare copper surface was evaluated. Joints of silicon dice on copper were fabricated by pressureless sintering of nanosilver paste in forming gas. All the joints survived 1000 temperature cycles in the temperature range of −40 °C to 125 °C and with a cycling period of 60 min. Die-shear test results showed that the average die-shear strength of joints had no significant drop after 1000 cycles and remained over 30 MPa. X-ray tomography and scanning electron microscopy (SEM) were applied to detect the cracks or delamination generated during cycling. X-ray images show no significant change on the delamination percentage of die-attach area during cycling. Cross-sectional SEM images of the joints show no delamination formed at the silver/copper interface after 1000 cycles. We believe that strong metallurgical bonding and low interdiffusion rate at the silver/copper interface contribute to such great temperature cycling reliability.

Temperature Cycling Reliability Assessment of Die Attachment on Bare Copper by Pressureless Nanosilver Sintering

Point-of-load converter at light load has low efficiency owing to the “fixed losses” such as core loss and ac winding loss. This paper focuses on two-dimensional (2-D) gapping of a ferrite core to shape inductance versus load current to reduce inductor loss at light load. Since the maximum inductance of conventional stepped gap is limited by the cross-sectional area of the thin gap, a 2-D gap is formed by joining two orthogonal gaps to gain flexibility. Higher inductance is achieved at light load compared with uniform-gap and stepped-gap geometries having the same volume and dc resistance. AC resistance is reduced at light load thanks to a magnetic path that steers ac flux away from the winding. Two C -cores with 2-D gap were fabricated and tested on a buck converter with 50% reduced total inductor loss at 10% load current.

Two-Dimensional Gapping to Reduce Light-Load Loss of Point-of-Load Inductor

The extended cantilever model is modified to enable broadband representation of multiple magnetic windings using s-domain transfer functions. A linear formulation for extracting the parameters is proposed in which the current-sense impedances do not have to be assumed negligible. The model has been implemented in a circuit simulator that supports transfer function blocks. It has been verified experimentally using a five-winding power transformer. The experimental transformer is simulated embedded in a two-transistor forward converter to examine simulation speed and convergence issues.

Broadband extended cantilever model for magnetic component windings

A commercial multi-extruder paste-extrusion 3D printer was used to process both metal and magnetic pastes into 3D structures of magnetic components for power electronics circuits. For the magnetic core, we formulated a permalloy powder filled benzocyclobutene composite in the form of paste, termed poly-mag paste, as a feed stock for the printer; while for the conductive winding feed stock, we used a commercial nanosilver paste. A toroid inductor was 3D-printed by using the metal and magnetic pastes, and it was cured at 250oC for a half hour without any external pressure to form the structure. The inductance of the 3D-printed toroid inductor was measured to be about 110.3nH. The DC resistance of the winding was 0.28Ω. Both the winding and core magnetic properties can be improved by adjusting the feed paste formulations and their flow characteristics and fine-tuning the printer parameters, such as motor speeds, extrusion rate, and nozzle sizes.

Additive manufacturing of toroid inductor for power electronics applications

In order to take full advantage of SiC, a high temperature wirebond package for multi-chip phase-leg power module using SiC devices was designed, developed, fabricated and tested. The details of the material selection and thermo-mechanical reliability evaluation are described. High temperature power test shows that the package presented in this paper can perform well at the high junction temperature.

Khai D. T. Ngo

Papers

Temperature Cycling Reliability Assessment of Die Attachment on Bare Copper by Pressureless Nanosilver Sintering

Two-Dimensional Gapping to Reduce Light-Load Loss of Point-of-Load Inductor

Broadband extended cantilever model for magnetic component windings

Additive manufacturing of toroid inductor for power electronics applications

SiC Wirebond Multi-Chip Phase-Leg Module Packaging Design and Testing for Harsh Environment