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

This paper presents a methodology for modeling a high-temperature silicon carbide (SiC) JFET-Junction-Barrier Schottky (JBS) Power Electronics Building Block (PEBB). The SiCED 1.2 kV, 5 A SiC JFET has been characterized and its model been built based on the SPICE 2 JFET model, which also includes other important features like the body diode and the gate breakdown diode. The electrical model of an actual JFET/JBS PEBB module, which is dedicated for high-temperature applications, has also been obtained using computer-aided 3-D electromagnetic analysis. The device and package models are then combined in the circuit simulation and verified through comparing simulation with experimental results. The simulation results obtained provide good insight into the effects that the package parasitic components have on the SiC devices, while enabling the study of the current sharing between dice, and the observation of their internal currents, capacitances and voltages.

Modeling and simulation of a high-temperature SiC JFET/JBS power electronics building block

This article presents a new method for generating low-frequency electromagnetic waves for navigation and communication in challenging environments, such as underwater and underground. The key concept is to disturb the magnetic energy stored around a permanent magnet in a time-variant fashion. The magnetic reluctance of the medium around the permanent magnet is modulated to alter the magnetic flux intensity and direction (disturb the stored energy) in order to achieve this goal. The nonlinear properties of the surrounding magnetic material are a critical phenomenon for efficient and effective modulation. Since the proposed way of generating the electromagnetic field is not based on a second-order system (resonant structure), the bandwidth of any modulation schema is not limited to the overall system quality factor. A transmitter is prototyped as a proof of concept, and the generated field is measured. Compared with the rotating magnet, the prototyped transmitter can modulate up to 50% of the permanent magnet’s stored energy with much lower power consumption.

New Way of Generating Electromagnetic Waves

Chip size (<inline-formula> <tex-math notation="LaTeX">${A}_{\text {chip}}$ </tex-math></inline-formula>) optimization is key to the accurate analysis of device and material costs and the design of multichip modules. It is particularly critical for wide bandgap (WBG) and ultrawide bandgap (UWBG) power devices due to high material cost. Moreover, the designs of <inline-formula> <tex-math notation="LaTeX">${A}_{\text {chip}}$ </tex-math></inline-formula> and the drift region thickness (<inline-formula> <tex-math notation="LaTeX">${W}_{\text {dr}}$ </tex-math></inline-formula>) and doping concentration (<inline-formula> <tex-math notation="LaTeX">${N}_{\text {dr}}$ </tex-math></inline-formula>) are interdependent, requiring their co-optimization. Current design practices for <inline-formula> <tex-math notation="LaTeX">${A}_{\text {chip}}$ </tex-math></inline-formula>, <inline-formula> <tex-math notation="LaTeX">${W}_{\text {dr}}$ </tex-math></inline-formula>, and <inline-formula> <tex-math notation="LaTeX">${N}_{\text {dr}}$ </tex-math></inline-formula> rely on optimizing electrical parameters.<inline-formula> <tex-math notation="LaTeX">$^{^{^{}}}$ </tex-math></inline-formula> This work presents a new, holistic, electrothermal approach to optimize <inline-formula> <tex-math notation="LaTeX">${A}_{\text {chip}}$ </tex-math></inline-formula> for a given set of target specifications, including breakdown voltage (BV), conduction current (<inline-formula> <tex-math notation="LaTeX">${I}_{{0}}$ </tex-math></inline-formula>), and switching frequency (<inline-formula> <tex-math notation="LaTeX">${f}$ </tex-math></inline-formula>). The conduction and switching losses of the device are considered as well as the heat dissipation in the chip and its package. For a given BV and <inline-formula> <tex-math notation="LaTeX">${I}_{\text {o}}$ </tex-math></inline-formula>, the optimal <inline-formula> <tex-math notation="LaTeX">${A}_{\text {chip}}$ </tex-math></inline-formula>, <inline-formula> <tex-math notation="LaTeX">${W}_{\text {dr}}$ </tex-math></inline-formula>, and <inline-formula> <tex-math notation="LaTeX">${N}_{\text {dr}}$ </tex-math></inline-formula> show a strong dependence on <inline-formula> <tex-math notation="LaTeX">${f}$ </tex-math></inline-formula> and thermal management. Such dependencies are missing in prior <inline-formula> <tex-math notation="LaTeX">${A}_{\text {chip}}$ </tex-math></inline-formula> design methods. This approach is applied to compare the optimal <inline-formula> <tex-math notation="LaTeX">${A}_{\text {chip}}$ </tex-math></inline-formula> of WBG and UWBG devices up to a BV over 10 kV and <inline-formula> <tex-math notation="LaTeX">${f}$ </tex-math></inline-formula> of 1 MHz.<inline-formula> <tex-math notation="LaTeX">$^{^{^{}}}$ </tex-math></inline-formula> Our approach offers more accurate cost analysis and design guidelines for power modules.

Chip Size Minimization for Wide and Ultrawide Bandgap Power Devices

A variable inductor concept based on a magnetic structure consisting of a composite of magnetic materials is introduced to meet designed inductance function of current. A design of the inductor, termed hetero-magnetic swinging inductor (HMSI), was fabricated using a toroid core with a gap that was filled by a custom-developed low-permeability magnetic powder + polymer material. Having the gap filled with the magnetic material allowed for greater flexibility in L-I design with added benefit of low fringe field. We applied this swinging inductor to a Critical Conduction Mode (CRM) Boost power factor correction (PFC) converter to reduce its switching frequency variation range. First, the required L-I curve of the HMSI needed for narrow range of switching frequency was calculated. Then, the HMSI core structure consisting of two magnetic materials was designed. Circuit simulations showed that for a 110-Vrms input, the converter with the HMSI had a switching frequency variation factor, defined as $\Delta\text{f}/\text{fmin}$ , six times less than that of the converter using a linear inductor. A prototype of the HMSI was fabricated and tested. The effectiveness of using the HMSI to narrow the range of switching frequency variation was verified in a 150 W CRM PFC converter.

Khai D. T. Ngo

Papers

Modeling and simulation of a high-temperature SiC JFET/JBS power electronics building block

New Way of Generating Electromagnetic Waves

Chip Size Minimization for Wide and Ultrawide Bandgap Power Devices

Hetero-Magnetic Swinging Inductor (HMSI) and Its Application for Power Factor Correction Converters

Thermal characterization of planar high temperature power module packages with sintered nanosilver interconnection