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

Over the years, electronic equipment, especially semiconductor based devices, have found their applications in almost all fields of research. The demand for more power and performance from such electronic equipment has constantly been growing resulting in an increased amount of heat dissipation from these devices. While conventional cooling solutions have performed the task of heat removal, no straightforward extension has been possible for significantly high heat fluxes dissipated by smaller and more efficient electronic devices. Thermal management of high-density power control unit for hybrid electric vehicle is one such challenging application. Over the last few years, the performance of this power control unit has been improved and size has been reduced to attain higher efficiency and performance causing the heat dissipation as well as heat density to increase significantly. Efforts are constantly being made to reduce the PCU size even further and also to reduce the manufacturing costs. As a consequence, heat density will go up (∼200–250 W/cm2) and thus, a better high performance cooler/heat exchanger is required which can operate under the existing cooling system design (pressure drop limitation) and at the same time, maintain active devices temperature within optimum range (<120–125°C) for higher reliability.The focus of this paper is to discuss the development of various cooling options for high heat flux dissipating devices with severe size constraints. A parametric and optimization study on the selected designs was performed. Finally, the optimized cooler/heat exchanger was tested under actual running conditions. The methodology was to explore various high performance cooling options such as impinging jets, pin fins, and ribbed mini-channels and to arrive at new promising, conceptual designs. These new designs were then compared against similar conventional designs both numerically and experimentally. Additionally, conjugate heat transfer simulations were performed on partial packaging model to compare the various designs. Experiments were also performed to validate the simulation models and characterize the meshing parameters to perform cost and time effective calculations/simulations.Copyright © 2012 by ASME

High Efficiency Minichannel and Mini-Impingement Cooling Systems for Hybrid Electric Vehicle Electronics

An accurate circuit model for transient behavior is necessary for transient thermal design and coupled electro-thermal simulation of complete power electronics system including semiconductor devices, thermal packages, and heat exchangers. Conventional thermal models of a power module are usually independent of boundary conditions, rendering these models ineffective in predicting the transient temperature of the thermal stacks as a function of heat-transfer coefficients. Thus, the paper presents an RC circuit model in which the thermal resistances and capacitances depend on the material properties and dimensions of the thermal layers, as well as the heat-transfer coefficient of the boundary. Only steady-state FEM simulation is needed to extract the model parameters. The boundary-dependent thermal model has been verified by simulation and experiment, which confirms that it is more accurate than the widely used thermal model based on assumption of 45° heat spreading.

Boundary-dependent circuit model for the transient behavior of a thermal stack in power modules

Tunable piezoelectric transformer (TPT) is a recently developed piezoelectric transformer with three ports: input, output and control ports. It can be treated as the integration of an LCC resonant tank and a transformer, where the series resonant capacitance can be tuned by the control port. There are two methods to design the output LC filter in TPT based converters. The traditional method is to place the output inductor after the rectifier. Such inductor is denoted by DC output inductor since it has a non-zero average current. The proposed method in this paper is to place output inductor before the rectifier. Such output inductor operates with zero average current and is denoted by AC output inductor. The regulation limitation caused by the DC output inductor is analyzed. This can be improved by the new resonance characteristic induced by the AC output inductor. The performance of TPT based converters with these two types of output inductors are compared. Experimental results show that the TPT based DC/DC converter with AC output inductor requires smaller output inductance and control capacitance than the one with DC output inductor. Also, the one with AC output inductor has better regulation and light load efficiency but worse full load efficiency.

A Comparison of DC and AC Output Inductors in Tunable Piezoelectric Transformer Based DC/DC Converters

Resonant inductor with significant ac flux at MHz switching frequency is challenging because of high core loss and winding loss due to skin and proximity effect. Air gap brings in fringing magnetic field resulting in uneven current distribution and therefore higher winding loss. The conventional rectangular-window core is replaced by the diamond-window core to reduce the fringing flux on the winding and therefore results in smaller inductor loss. An inductor prototype was built and was placed into a 200W Series-Resonator Buck (SRB) converter at 48V input voltage and 40A output. Experimental results are discussed to verify the theoretical analysis.

Diamond-Window Resonant Inductor with Significant AC Flux

A variable inductor concept based on a magnetic structure consisting of composite of magnetic materials is introduced to meet the designed inductance function of current. A design of the inductor, termed heteromagnetic 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. The analytical model of HMSI was derived and verified by simulation. And the step-by-step design of arbitrary L–I curve HMSI was posted. We applied this swinging inductor to a critical conduction mode boost power factor correction 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. Finally, a prototype of the HMSI was fabricated and tested. Experimental result showed that for a 110-Vrms input, the converter with the HMSI had a switching frequency variation factor, defined as Δ f / f min, six times less than that of the converter using a linear inductor.

Khai D. T. Ngo

Papers

High Efficiency Minichannel and Mini-Impingement Cooling Systems for Hybrid Electric Vehicle Electronics

Boundary-dependent circuit model for the transient behavior of a thermal stack in power modules

A Comparison of DC and AC Output Inductors in Tunable Piezoelectric Transformer Based DC/DC Converters

Diamond-Window Resonant Inductor with Significant AC Flux

Heteromagnetic Swinging Inductor and Its Application for Power Factor Correction Converters