Hardware Placement Research Articles

Optimization models for ATM network planning

This article describes mathematical programming models that have been developed and employed to evaluate configuration strategies for metropolitan ATM telecommunication networks. The models determine the optimal placement of ATM switch hardware and fiber optic transport. The objective is to satisfy point-to-point traffic demand at minimum cost while ensuring specified performance under a core failure contingency. Model results suggest that a simple architecture based on two core switch locations provides a robust, near-optimal solution. Scope and purpose Communication service providers face a future market environment characterized by dramatically increasing demand and dominance of data services over voice services. One approach to achieving a “data-centric” network architecture relies on Asynchronous Transfer Mode (ATM) technology, in which all types of traffic (voice, data, video, etc.) are converted to common data packets. The optimization models described in this article support an effective application of ATM technology to ensure that customer service demands are satisfied in a reliable and cost-efficient manner.

Orthopaedic Implant-Related Sarcoma: A Study of Twelve Cases

Sarcoma developing in association with a metallic orthopaedic prosthesis or hardware is an uncommon, but well recognized complication. We review 12 cases of sarcomas arising in bone or soft tissue at the site of orthopaedic hardware or a prosthetic joint. Nine patients were male, and three were female. Their ages ranged from 18 to 85 (mean 55) years at the time of diagnosis of the malignancy. Five patients had undergone hip arthroplasty for degenerative joint disease, four had been treated with intramedullary nail placement for fracture, two had staples placed for fixation of osteotomy, and one had hardware placed for fracture fixation followed years later by a hip arthroplasty. The time interval between the placement of hardware and diagnosis of sarcoma was known in 11 cases and ranged from 2.5 to 33 (mean 11) years. The patients presented with pain, swelling, or loosening of hardware and were found to have a destructive bone or soft tissue mass on radiography. Two sarcomas were located primarily in the soft tissue and 10 in bone. Seven patients developed osteosarcoma, four malignant fibrous histiocytoma, and one a malignant peripheral nerve sheath tumor. All sarcomas were high grade. Three patients had metastatic disease at the time of diagnosis. Follow-up was available on eight patients: five patients died of disease 2 months to 8 years (mean 26 months) after diagnosis; two patients died without evidence of disease 7 and 30 months after diagnosis; and one patient is alive and free of disease 8 years after diagnosis. Sarcomas that occur adjacent to orthopaedic prostheses or hardware are of varied types, but are usually osteosarcoma or malignant fibrous histiocytoma. They behave aggressively and frequently metastasize. Clinically, they should be distinguished from non-neoplastic reactions associated with implants, such as infection and a reaction to prosthetic wear debris.

An implementation of fuzzy logic controller on the reconfigurable FPGA system

This paper concerns an implementation of a fuzzy logic controller (FLC) on a reconfigurable field-programmable gate array (FPGA) system. In the proposed implementation method, the FLC is partitioned into many temporally independent functional modules, and each module is implemented individually on the FLC automatic design and implementation system, which is an integrated development environment for performing many subtasks such as automatic VHSIC hardware description language description, FPGA synthesis, optimization, placement and routing, and downloading. Each implemented module forms a downloadable hardware object that is ready to configure the FPGA chip. Then, the FPGA chip is consequently reconfigured with one module at a time by using the run-time reconfiguration method. This implementation method is effective when a single FPGA chip cannot fit the FLC due to the limited size of its constituent cells. We test the proposed implementation method by building the FLC for the truck backer-upper control on VCC Corporation's EVC-1 reconfigurable FPGA board directly.

Intraoperative fluoroscopy to evaluate fracture reduction and hardware placement during acetabular surgery.

To evaluate use of intraoperative fluoroscopy during acetabular surgery to determine fracture reduction and accurate placement of screws. Retrospective. Level I trauma center. Thirty patients with thirty-two acetabular fractures. Patients were evaluated with fluoroscopy during surgery to assess fracture reduction and screw placement. Anterior-posterior (AP), oblique, and lateral pelvic fluoroscopic images were obtained intraoperatively. Postoperative radiographs were used to verify fluoroscopic findings; computed tomography (CT) scans were used as the control to assess intraarticular screw placement. Radiographic and clinical assessment of fracture reduction and screw placement. Intraoperative fluoroscopy confirmed the extra-articular position of all screws evaluated. Postoperative CT scans confirmed the extra-articular placement of all screws assessed by fluoroscopy. Quality of reduction using intraoperative fluoroscopic images had a 100 percent correlation with reduction on final radiographs. One patient, with two screws placed without fluoroscopic evaluation, had intra-articular placement requiring revision surgery. Intraoperative fluoroscopy is effective in evaluating both acetabular fracture reduction and hardware placement.

Exploring Frameless Stereotactic Image Guided Surgery

Frameless stereotactic image guided surgery (IGS)--a fairly new modality originally used in cranial neurosurgical procedures--has been found to have several advantages over traditional framed methods of three-dimensional navigation. Frameless stereotactic IGS is proving useful in neurosurgical procedures by allowing screws to be placed in the spine more quickly and accurately than with traditional methods. As IGS becomes standard clinical practice for certain spinal procedures--overlapping both neurosurgery and orthopedic specialties--new ideas for surgical application of the technology are developing. Currently, frameless stereotactic IGS is being investigated for use in hardware placement in orthopedic procedures and for endoscopic navigation in otorhinolaryngologic sinus procedures. Frameless stereotactic IGS is expected to gain application approval in both orthopedic and otorhinolaryngologic specialties from the US Food and Drug Administration in the near future.

Portable mini-fluoroscopy improves operative efficiency in hand surgery.

A paired case cohort study was performed using retrospective review of operative times for defined hand surgical procedures in an attempt to quantify efficiency with and without the use of portable fluoroscopy. Patients included in the study underwent 1 of 4 defined surgical procedures controlled to ensure similar operative technique (total wrist fusion, in situ 4-corner fusion, closed reduction/internal fixation using K-wires of phalangeal shaft fractures, and metacarpophalangeal or interphalangeal joint fusions using K-wires). One group used intraoperative standard film radiographs and the other used portable mini-fluoroscopy to examine hardware placement. Both groups were paired by operative procedure to eliminate procedure bias on overall operating time. Analysis demonstrated a 38% reduction in total operative time in the group using portable mini-fluoroscopy compared with standard intraoperative radiographs.

Transverse lag screw fixation of the midline mandibulotomy.

Transverse lag screw osteosynthesis of the midline mandibulotomy is a rapidly performed technique that results in reestablishment of mandibular integrity and avoids placement of hardware directly beneath a suture line. We have performed transverse lag screw osteosynthesis in four patients over the past 14 months. All patients received postoperative radiotherapy. Soft-tissue and bone healing have been uneventful.

Modified Tension Band Wiring of Medial Malleolar Ankle Fractures

Twenty-two displaced medial malleolar ankle fractures that were treated surgically using the modified tension band method of Cleak and Dawson were retrospectively reviewed at an average follow-up of 25 months. The technique involves the use of a screw to anchor a figure-of-eight wire. There were no malreductions and all fractures healed. Problems with the technique included technical errors with hardware placement, medial ankle pain, and asymptomatic wire migration. Despite this, modified tension band wiring remains an acceptable method for fixation of selected displaced medial malleolar fractures. It is especially suited for small fracture fragments and osteoporotic bone.

Data integrity analysis of disk array systems with analytic modeling of coverage

Detailed dependability models of various disk array organizations are developed taking into account both the hard disk failures and transient errors. Various error and failure modes of individual disks and the disk array are identified. A small proportion of transient errors account for uncovered failures in a disk array. This leads to analytic computation of probability of disk failures based on several factors including byte error rate of a disk and ECC code etc. Traditionally used measures like MTTDL and data availability remain virtually unchanged with change in mean recovery time. New dependability measures such as degraded capacity time are considered to bring out the effect of mean recovery time on dependability of disk arrays. Our analysis also reveals that mirrored disk organization has higher MTTDL than other disk array organizations if the only failure mode considered is data loss while catastrophic errors are ignored. However, if catastrophic errors are taken into account, then RAID-3,4,5 organizations have higher data-integrity than other disk array schemes. We also develop models that take into account the reliability of support hardware components and different placement schemes for arranging support hardware such as power supply. Our analysis reveals that RAID-1 benefits the most from orthogonal placement of support hardware.

Acetabular Fracture Fixation Via a Modified Stoppa Limited Intrapelvic Approach Description of Operative Technique and Preliminary Treatment Results

Between March 1991 and December 1992 the authors surgically treated 55 acetabular fractures using a modified Stoppa anterior intrapelvic extensile approach. Indications for utilization of this approach included displaced anterior column or wall fractures, transverse fractures, T shaped fractures, both column fractures and anterior column or wall fractures associated with a posterior hemitransverse component. The approach involves a transverse skin incision 2 cm above the pubic symphysis followed by a midline split of the rectus abdominis. Access to the intrapelvic aspect of the pelvis and acetabulum is gained by retraction of the muscular, neurovascular and urological structures. This modified Stoppa approach affords excellent visualization of the pelvic ring, facilitating the development and utilization of improved reduction and plating options. Patients were followed for an average of 17.7 months. All fractures united 6-12 weeks postoperatively. Radiographic grades were excellent (64%), good (25%), fair (7%) and poor (4%). Fixation and subsequent reduction were lost in 1 patient. Two transient obturator nerve palsies were diagnosed. There was 1 infection and 1 inguinal hernia. Posttraumatic arthritic changes were noted in 6 patients within the first postoperative year. There was no significant heterotopic ossification, major vascular injury iatrogenic palsy or intraarticular hardware placement. Clinical results were excellent (47%), good (42%), fair (9%) and poor (2%). The modified Stoppa incision offers the experienced trauma surgeon a new approach for fixation of displaced acetabular fractures. The approach offers improved reduction and fixation possibilities and may decrease the rate of complications associated with extrapelvic or extensile approaches.

Application of fault modeling to continuous built‐in test (c‐BIT) for microwave and MMIC circuits

AbstractA simulation‐before‐test method has been applied to the linear and nonlinear microwave built‐in test (BIT) problem. Fault simulation via a harmonic balance simulator is used to analyze and optimize BIT hardware placement based on figures of merit such as fault coverage, ambiguity size, and part isolation. Fault models for a prototype microwave mini‐system were developed along with models for the BIT hardware itself. The search method developed to automate the placement of BIT hardware is an essential design‐for‐test tool. The techniques developed were applied to an example system and results are given.

Single-mode fibers used as confocal microscope pinholes

Conventional clear-aperture pinholes in confocal microscopes can be replaced by single-mode optical fibers, thereby reducing alignment and dust accumulation problems and providing greater flexibility for optical and electronic hardware placement.

Automatic Implantable Cardioverter Defibrillators: Surgical Approaches for Optimal Function

The automatic implantable car dioverter defibrillator (AICD) has significantly enhanced the treatment of malignant tachyarrhythmia but has complex requirements for contin uous function. Forty-nine patients (pts, ages nine to seventy-nine) from 377 pts studied for life-threatening tachyarrhythmias (13%) underwent AICD hardware placement during the first forty-eight months of clinical investigation. Access was dictated by (1) prior operative procedures (17 pts), (2) adequate sensing thresholds (12 pts), and (3) low thresholds (ie, s 15 watts) for successful defibrilla tion configuration (21 pts). Late com plications and morbidity (26 pts, 53%) have been the rule, the most common due to: (A) generator fail ures (15 pts), (B) patches or lead mal positions (4 pts), (C) inappropriate sensing from lead failures (3 pts), and (D) required explanations (leads only for 2 pts and units for 2 pts). There has been only 1 operative death among the 49 pts and none for the 21 revisions and generator changes (overall 1/70 procedures, 1.4%). However, survivals at one, two, and three years were 82%, 56%, and 40% respectively with the majority of late deaths attributed to congestive heart failure (CHF). In summary, (1) AICD morbidity remains frequent but can be mini mized. Incidental placement should be avoided owing to associated mor bidity (explantation). (2) Optimal configurations usually require (a) ep icardial access, (b) patches directed at the ventricular focus for lower de fibrillation thresholds, (c) generator implantation adjusted for habitus, growth in children, and frequent generator failure. (3) Long-term sur vival has been poor in patients with associated CHF.

Location of Software in Distributed Computing Systems

The planning and design of computer networks give rise to many location problems. These may be split into those primarily concerned with placement of hardware and those with software. Here, a broad overview of location of software components (programs and data files) is given, together with a brief appraisal of the state-of-the-art for various problems.

Location Problems Arising in Computer Networks

The planning and organization of computer networks give rise to many location problems. These may be split into those primarily concerned with placement of hardware and those with software. Here a broad overview of location and hardware components is given, together with a brief appraisal of the ‘state of the art’ for various problems.

Self-test. the solution to the VLSI test problem?

Built-in self-test (BIST) is emerging as an important option for testing VLSI application-specific integrated circuits (ASICs). The advantages of BIST are reviewed in relation to the particular test requirements imposed by ASICs. A suite of programs will be described that facilitate the incorporation of BIST into ASIC designs. The programs comprise a high-level planning tool, operating from functional descriptions of the circuit. A set of programs will also be described that enable the evaluation of the fault coverage achieved when circuits are tested using pseudorandom patterns, and also aid the placement of additional test hardware to improve the level of fault coverage.

Aortic laceration after anterior spinal fusion

Six weeks after anterior spinal fusion and instrumentation for a burst fracture of the second lumbar vertebra, a patient developed a nearly fatal retroperitoneal hemorrhage from a laceration of the aorta produced by the metallic implant. This experience suggests that placement of fusion hardware in close proximity to large arteries should be avoided if possible or, if such placement is necessary, the device should be removed as soon as fusion has taken place.