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Showing papers by "Ford Motor Company published in 1996"


Book
01 Jan 1996
TL;DR: In this article, the authors present a review of rigor properties of low-dimensional models and their applications in the field of fluid mechanics. But they do not consider the effects of random perturbation on models.
Abstract: Preface Part I. Turbulence: 1. Introduction 2. Coherent structures 3. Proper orthogonal decomposition 4. Galerkin projection Part II. Dynamical Systems: 5. Qualitative theory 6. Symmetry 7. One-dimensional 'turbulence' 8. Randomly perturbed systems Part III. 9. Low-dimensional Models: 10. Behaviour of the models Part IV. Other Applications and Related Work: 11. Some other fluid problems 12. Review: prospects for rigor Bibliography.

2,920 citations


Journal ArticleDOI
TL;DR: Prior insomnia remained a significant predictor of subsequent major depression when history of other prior depressive symptoms was controlled for, and complaints of 2 weeks or more of insomnia nearly every night might be a useful marker of subsequent onset of major depression.

1,670 citations


Journal ArticleDOI
TL;DR: Public policy to discourage early smoking, if it succeeds in delaying the initiation of smoking, might contribute to the reduction of smoking-related mortality and morbidity by increasing the potential for quitting.
Abstract: OBJECTIVES. Previous research has suggested that early smoking initiation predicts longer duration of smoking, heavier daily consumption, and increased chances of nicotine dependence. This report set out to estimate the relationship between smoking cessation and age of initiation, as well as nicotine dependence, sex, race, and education. METHODS. A sample of 1007 young adults was randomly selected from a large health maintenance organization in southeast Michigan. Hazard ratios of quitting associated with age at smoking initiation were estimated among 414 persons who smoked daily for 1 month or more. RESULTS. With potential confounders controlled for, the likelihood of cessation was significantly higher in smokers who initiated smoking after age 13. The hazard ratio for quitting associated with smoking initiation at ages 14 to 16 was 1.6 and with initiation at or after age 17 was 2.0, compared with initiation at or before 13 years of age. Factors that decreased the likelihood of cessation were nicotine de...

677 citations


Book
23 Oct 1996
TL;DR: Turning Boring Drilling Reaming Milling Planing and Shaping Broaching Tapping and Threading Grinding and Related Abrasive Processes Roller Burnishing Deburring Examples Problems References MACHINE TOOLS Introduction Production Machine Tools CNC Machine Tools and Cellular Manufacturing Systems Machine Tool Structures Slides and Guideways Axis Drives Spindles Coolant Systems Tool Changing Systems.
Abstract: INTRODUCTION Scope of the Subject Historical Development Types of Production References METAL CUTTING OPERATIONS Introduction Turning Boring Drilling Reaming Milling Planing and Shaping Broaching Tapping and Threading Grinding and Related Abrasive Processes Roller Burnishing Deburring Examples Problems References MACHINE TOOLS Introduction Production Machine Tools CNC Machine Tools and Cellular Manufacturing Systems Machine Tool Structures Slides and Guideways Axis Drives Spindles Coolant Systems Tool Changing Systems Examples References CUTTING TOOLS Introduction Cutting Tool Materials Tool Coatings Basic Types of Cutting Tools Turning Tools Boring Tools Milling Tools Drilling Tools Reamers Threading Tools Grinding Wheels Microsizing and Honing Tools Burnishing Tools Examples Problems References TOOLHOLDERS AND WORKHOLDERS Introduction Toolholding Systems Toolholder/Spindle Connections Cutting Tool Clamping Systems Balancing Requirements for Toolholders Fixtures Examples Problems References MECHANICS OF CUTTING Introduction Measurement of Cutting Forces and Chip Thickness Force Components Empirical Force Models Specific Cutting Power Chip Formation and Primary Plastic Deformation Tool-Chip Friction and Secondary Deformation Shear Plane and Slip Line Theories for Continuous Chip Formation Shear Plane Models for Oblique Cutting Shear Zone Models Minimum Work and Uniqueness Assumptions Finite Element Models Discontinuous Chip Formation Built-up Edge Formation Examples Problems References CUTTING TEMPERATURES Introduction Measurement of Cutting Temperatures Factors Affecting Cutting Temperatures Analytical Models for Steady-State Temperatures Finite Element and Other Numerical Models Temperatures in Interrupted Cutting Temperatures in Drilling Thermal Expansion Examples Problems References MACHINING PROCESS ANALYSIS Introduction Turning Boring Milling Drilling Force Equations and Baseline Data Process Simulation Examples Finite Element Analysis for Clamping, Fixturing, and Workpiece Distortion Applications Finite Element Application Examples Examples Problems References TOOL WEAR AND TOOL LIFE Introduction Types of Tool Wear Measurement of Tool Wear Tool Wear Mechanisms Tool Wear--Material Considerations Tool Life Testing Tool Life Equations Prediction of Tool Wear Rates Tool Fracture and Edge Chipping Drill Wear and Breakage Thermal Cracking and Tool Fracture in Milling Tool Wear Monitoring Examples Problems References SURFACE FINISH AND INTEGRITY Introduction Measurement of Surface Finish Surface Finish in Turning and Boring Surface Finish in Milling Surface Finish in Drilling and Reaming Surface Finish in Grinding Residual Stresses in Machined Surfaces White Layer Formation Surface Burn in Grinding Examples Problems References MACHINABILITY OF MATERIALS Introduction Machinability Criteria, Tests, and Indices Chip Control Burr Formation and Control Machinability of Engineering Materials References MACHINING DYNAMICS Introduction Vibration Analysis Methods Vibration of Discrete (Lumped Mass) Systems Types of Machine Tool Vibration Forced Vibration Self-Excited Vibrations (Chatter) Chatter Prediction Vibration Control Active Vibration Control Examples References MACHINING ECONOMICS AND OPTIMIZATION Introduction Role of a Computerized Optimization System Economic Considerations Optimization of Manufacturing Systems--Basic Factors Optimization of Machining Conditions Formulation of the Optimization Problem Optimization Techniques Numerical Examples Problems References CUTTING FLUIDS Introduction Types of Cutting Fluids Coolant Application Filtering Condition Monitoring and Waste Treatment Health and Safety Concerns Dry and Near-Dry Machining Methods Test Procedure for Cutting Fluid Evaluation References HIGH THROUGHPUT AND AGILE MACHINING Introduction High Throughput Machining Agile Machining Systems Tooling and Fixturing Materials Handling Systems References DESIGN FOR MACHINING Introduction Machining Costs General Design for Machining Rules Special Considerations for Specific Types of Equipment and Operations CAPP and DFM Programs Examples References INDEX

660 citations


Journal ArticleDOI
TL;DR: Investigation of multiple endocrine neoplasia type 1 patients found that parathyroid tumours were the first manifestation of MEN1 in 87% of patients, and amongst the pituitary and pancreatic tumours, somatotrophinomas and gastrinomas were more common in patients above the age of 40 years, whilst insulinomas occurred more frequently in patients below the ageof 40 years.
Abstract: Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant disorder characterized by the combined occurrence of parathyroid, pancreatic islet and anterior pituitary tumours. To facilitate a screening programme for MEN1, we investigated 709 people (364 males and 345 females, age range 1-84 years) from 62 MEN1 families, and 36 non-familial MEN1 patients. Of those investigated, 220 (95 males and 125 females, age range 8-79 years) suffered from MEN1. Parathyroid, pancreatic and pituitary tumours occurred in 95%, 41% and 30% of the patients, respectively. Parathyroid tumours were the first manifestation of MEN1 in 87% of patients, and amongst the pituitary and pancreatic tumours, somatotrophinomas and gastrinomas were more common in patients above the age of 40 years, whilst insulinomas occurred more frequently in patients below the age of 40 years. Biochemical screening indicated that the penetrance of MEN1 by the ages of 20, 35 and 50 years was 43%, 85% and 94%, respectively, and that the development of MEN1 was confined to first-degree relatives in 91% of patients and to second-degree relatives in 9% of patients. These findings have helped to define a proposed screening programme for MEN1.

449 citations


Journal ArticleDOI
TL;DR: In this paper, numerical and analytical models of magnetorheological fluid phenomena that account explicitly for the effects of magnetic nonlinearity and saturation are described, and the field-dependent stress required to shear the chains was then obtained using the Maxwell stress tensor.
Abstract: Numerical and analytical models of magnetorheological fluid phenomena that account explicitly for the effects of magnetic nonlinearity and saturation are described. Finite-element analysis was used to calculate the field distribution in chains of magnetizable particles. The field-dependent stress required to shear the chains was then obtained using the Maxwell stress tensor. Three regimes are identified: at low applied fields, the stress increase quadratically, as expected from linear magnetostatics. In intermediate fields, the contact or polar regions of each particle saturate, reducing the rate of increase of the stress with increasing field. At high fields, the particles saturate completely, and the stress reaches its limiting value. Approximate analytical expressions for the yield stress and shear modulus in these regimes are also derived. The predictions of these models are compared to magnetorheological experiments in the literature and from our laboratory. These models predict successfully the magn...

415 citations


Journal ArticleDOI
TL;DR: In this paper, the authors examined the relationship between employee attitudes, organizational unit performance, customer satisfaction, and turnover at the branch level for a large automobile finance company, using data from 142 branches in 2 consecutive years.
Abstract: Recent evidence has suggested that attitudes-organizational effectiveness relations may exist. Relations between employee attitudes, organizational unit performance, customer satisfaction, and turnover were examined at the branch level for a large automobile finance company. Using data from 142 branches in 2 consecutive years, several significant relations between attitude factors and performance were observed. In addition, causal analyses conducted at the branch level suggested that customer satisfaction led to employee attitudes, rather than the opposite. Additional analyses to explain this result suggested that economic conditions and related factors might be the causal mechanism at the aggregated level. Other potential interpretations of these findings and caveats about generalizing organizational-level findings to the individual level are discussed.

383 citations


Journal Article
TL;DR: It is concluded that morphological and biochemical features of cardiocyte apoptosis exist in the left ventricular myocardium of dogs with chronic heart failure.
Abstract: It is often speculated that progressive deterioration of left ventricular function in heart failure is due to ongoing loss of viable cardiocytes. In this study, we examined the possibility that cardiocyte loss in heart failure may be due, in part, to apoptosis, an active process of gene-directed cellular self-destruction. Studies were performed in left ventricular tissue obtained from 10 dogs with chronic heart failure produced by multiple intracoronary microembolizations (left ventricular ejection fraction 27 +/- 1%) and from 5 normal dogs. Evidence for cardiocyte apoptosis was based on transmission electron microscopy criteria and on in situ immunohistochemical labeling of nuclear DNA fragmentation. There was no evidence of apoptotic cardiocytes in normal dogs. Features of cardiocyte apoptosis were observed in dogs with heart failure primarily in regions bordering old infarcts. Electron microscopic features of cardiocyte apoptosis included (1) intact sarcolemma and inner organelles in the presence of compaction and segregation of nuclear chromatin into sharply delineated masses that about the nuclear envelope, (2) intact sarcolemma in the presence of cytoplasm shrinkage, blebbing, and nuclear fragmentation, and (3) intact sarcolemma in the presence of complete disorganization of inner organelles and disappearance of nucleolemma. A count of all of the apoptotic bodies positively labeled for nuclear DNA fragments showed that 11% were of cardiocyte origin confirmed by positive labeling with striated muscle antimyosin antibody. We conclude that morphological and biochemical features of cardiocyte apoptosis exist in the left ventricular myocardium of dogs with chronic heart failure.

349 citations


Journal ArticleDOI
14 Dec 1996-BMJ
TL;DR: This work aimed to assess the prevalence and types of psychiatric disorder among adolescents in the care system and compare them with those of a comparison group of adolescents.
Abstract: Recently, professional and political concern has grown about the severity and types of problems experienced by young people in the care system, this group being one of the most vulnerable in terms of psychological disturbance. Their risk of psychiatric ill health is higher than that of any other easily identified group in our society,1 and studies have consistently identified a high incidence of behavioural problems.2 No study has systematically examined the psychiatric disorders of adolescents being looked after by local authorities, so we aimed to assess the prevalence and types of psychiatric disorder among adolescents in the care system and compare them with those of a comparison group of adolescents. All adolescents aged 13 to 17 years looked after by the Oxfordshire local authority—that is, living in residential …

328 citations


Journal ArticleDOI
TL;DR: In this paper, global stress functions are used to approximate local stresses and the density method is employed for solving the topology optimization problems, and three numerical examples are used for this investigation.
Abstract: Previous research on topology optimization focussed primarily on global structural behaviour such as stiffness and frequencies. However, to obtain a true optimum design of a vehicle structure, stresses must be considered. The major difficulties in stress based topology optimization problems are two-fold. First, a large number of constraints must be considered, since unlike stiffness, stress is a local quantity. This problem increases the computational complexity of both the optimization and sensitivity analysis associated with the conventional topology optimization problem. The other difficulty is that since stress is highly nonlinear with respect to design variables, the move limit is essential for convergence in the optimization process. In this research, global stress functions are used to approximate local stresses. The density method is employed for solving the topology optimization problems. Three numerical examples are used for this investigation. The results show that a minimum stress design can be achieved and that a maximum stiffness design is not necessarily equivalent to a minimum stress design.

299 citations


Journal ArticleDOI
TL;DR: A global stabilization procedure for nonlinear cascade and feedforward systems which extends the existing stabilization results and gives conditions for continuous differentiability of the Lyapunov function and the resulting control law.
Abstract: We present a global stabilization procedure for nonlinear cascade and feedforward systems which extends the existing stabilization results. Our main tool is the construction of a Lyapunov function for a class of (globally stable) uncontrolled cascade systems. This construction serves as a basis for a recursive controller design for cascade and feedforward systems. We give conditions for continuous differentiability of the Lyapunov function and the resulting control law and propose methods for their exact and approximate computation.

Journal ArticleDOI
TL;DR: Mental stress-induced myocardial ischemia is associated with a significant increase in systemic vascular resistance and a relatively minor increase in heart rate and rate-pressure product compared with ischemIA induced by exercise.
Abstract: Background The pathophysiology of mental stress–induced myocardial ischemia, which occurs at lower heart rates than during physical stress, is not well understood. Methods and Results The Psychophy...

Patent
11 Dec 1996
TL;DR: In this paper, a vehicle user can request emergency or roadside assistance from a response center by activating a button in the vehicle and the global positioning system is used to continuously store the vehicle location.
Abstract: A vehicle user can request emergency or roadside assistance from a response center by activating a button in the vehicle. The global positioning system is used to continuously store the vehicle location. A cellular telephone network is used to contact a response center and transfer a data string via modem containing information to assist the response center in acting on the request. If a first attempt to contact the response center at a phone number for receiving a data transfer is unsuccessful, a second call is made to a different number bypassing the data transfer and immediately placing the cellular phone into an unmuted condition. This allows the user to hear and interact with a cellular operator, if necessary, prior to being connected to the response center.

Patent
13 Dec 1996
TL;DR: In this article, a method and apparatus for desulfating a NO x trap is proposed, where the SO x purge temperature is achieved by modulating the amplitude of the A/F of the mixture supplied to the engine.
Abstract: A method and apparatus for desulfating a NO x trap is proposed wherein the SO x purge temperature is achieved by modulating the amplitude of the A/F of the mixture supplied to the engine thereby storing oxygen in the trap during lean engine cylinder events and generating the required exotherm during rich engine cylinder events.

Journal ArticleDOI
TL;DR: The role of exercise training in the treatment of heart failure remains a paradox, because exercise intolerance is a characteristic finding in patients with this condition and the mechanisms by which this improvement occurs are uncertain.
Abstract: Objective: To assess the benefit of exercise training in patients with heart failure caused by left ventricular systolic dysfunction and to further describe the physiologic changes associated with ...

Journal ArticleDOI
TL;DR: It is demonstrated that administration of PROG to the male rat before or 2 hours after onset of MCAO reduces ischemic cell damage and improves physiological and neurological function 2 days after stroke, suggesting potential therapeutic properties of PROG in the management of stroke.

Journal ArticleDOI
01 Nov 1996-Stroke
TL;DR: The NINDS t-PA Stroke Trial as discussed by the authors was a randomized, double-blind, placebo-controlled trial of recombinant tissue plasminogen activator (rt-PA) for patients with acute ischemic stroke.
Abstract: Background The National Institute of Neurological Disorders and Stroke (NINDS) held a workshop on statistical approaches to analysis of acute stroke trials that have multiple prespecified outcomes. An objective was to plan for statistical analysis of the NINDS t-PA Stroke Trial, a randomized, double-blind, placebo-controlled trial of recombinant tissue plasminogen activator (rt-PA) for patients with acute ischemic stroke. Treatment success was defined as a “consistent and persuasive difference” in the proportion of patients achieving favorable outcomes on the Barthel Index, Modified Rankin Scale, Glasgow Outcome Scale, and National Institutes of Health Stroke Scale. The Data and Safety Monitoring Committee for the trial recommended this outcome because the committee did not believe that a positive result for a single outcome would provide sufficient evidence of efficacy. Summary of Comment Workshop participants accepted the global test as a viable approach to testing the primary trial hypothesis. Clinicia...

Patent
16 Oct 1996
TL;DR: In this paper, a method and apparatus for on-board monitoring of NO x trap performance is proposed that uses two HEGO sensors, one positioned upstream of the NOx trap, and the other positioned downstream of the trap.
Abstract: A method and apparatus for on-board monitoring of NO x trap performance is proposed that uses two HEGO sensors, one positioned upstream of the NO x trap, and the other positioned downstream of the NO x trap. When the engine A/F is reduced from lean to stoichiometric or rich operation to regenerate or purge the NO x trap the difference in the time it takes for the upstream and downstream HEGO sensors to switch from a lean to a rich indication provides a quantitative measure of the amount of NO x that was stored on the NO x trap during the previous lean period of operation. This measure is related to an estimated amount of NO x produced by the engine to infer the operating performance or efficiency of the NO x trap. The difference in the output voltage of the two sensors is compared with a predetermined value to determined when to terminate the NO x purge. When the efficiency drops below a predetermined value the time that the engine is run in a lean cruise mode is reduced. If the time is reduced below a minimum time interval, a sulfur purge is performed. If sulfur purges are required more often than a predetermined repetition time, the lean cruise mode is terminated and an indicator lamp is energized.

Journal ArticleDOI
TL;DR: In this article, a survey of different internal combustion engine models and arid control design methodologies for the idle speed control (ISC) application is presented, including both classical designs, often seen in production, and those based on advanced control theory such as H.~ and l~ control.

Journal ArticleDOI
TL;DR: Treatment with anti-adhesion molecule antibodies selectively reduce apoptosis, and that a contributing factor to the beneficial effect of antibody treatment for reducing ischemic cell damage may be a reduction in numbers of apoptotic cells.
Abstract: We tested the hypothesis that treatment of transient focal cerebral ischemia in rat with antibodies directed against adhesion molecules reduces apoptosis. Rats (n = 31) were subjected to 2 h of middle cerebral artery (MCA) occlusion induced by intraluminal insertion of a nylon monofilament into the internal carotid artery. Upon reperfusion, animals were treated with monoclonal antibodies directed against intercellular adhesion molecule (ICAM)-1) (n = 8) or integrin CD11b/CD18 (n = 10), or administered IgG1 as a control (n = 13). At 48 h after ischemia, animals were killed and the brains analyzed for ischemic cell damage, using hematoxylin and eosin (H/E); apoptosis, using the terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labeling (TUNEL) method; and inflammatory cells, using immunohistochemistry with an anti-myeloperoxidase (MPO) antibody. Data revealed a significant reduction in the volume of infarction (p < 0.01) and a decline in the absolute (p < 0.001), and normalized (to the ischemic areas, p < 0.05) numbers of apoptotic cells in both animals treated with anti-ICAM-1 and anti-CD11b antibodies compared to control animals. The numbers of immunoreactive MPO cells were also reduced in the treatment groups compared to those in the control group (p < 0.05). These data suggest that treatment with anti-adhesion molecule antibodies selectively reduce apoptosis, and that a contributing factor to the beneficial effect of antibody treatment for reducing ischemic cell damage may be a reduction in numbers of apoptotic cells.

Patent
12 Dec 1996
TL;DR: In this article, a method and system for facilitating a transaction between a customer and an automobile dealership is described. The system includes a kiosk including an input/display terminal and a terminal processor for formulating a multilevel customer query of automobile inventory.
Abstract: The invention relates to a method and system for facilitating a transaction between a customer and an automobile dealership. The system includes a kiosk including an input/display terminal and a terminal processor for formulating a multilevel customer query of automobile inventory. The query searches a storage device containing automobile data and images to return a selected inventory to the input/display device. The practice of the invention includes storing customer data, selected inventory information for later access by a marketing follow-up application and a financing and insurance application.

Journal ArticleDOI
TL;DR: Increased sialylation of mucin-associated carbohydrates is characteristic of colon cancer cells that are most likely to metastasize, and plays a role in adhesive interactions involving both basement membrane and endothelial-associated ligands.

Journal ArticleDOI
01 Jan 1996-Chest
TL;DR: Blood gas levels are of insufficient discriminant value to permit exclusion of the diagnosis of PE, and other combinations of blood gas levels and the P(A-a)O2 gradient, failed to exclude PE in larger percentages of patients.


Patent
05 Aug 1996
TL;DR: In this article, a multi-cylinder spark ignition internal combustion engine is described with two groups of cylinders and one group of cylinders may be selectively disabled by cutting off its fuel supply while continuing to receive air.
Abstract: A multi-cylinder spark ignition internal combustion engine is described having two groups of cylinders (10a, 10b). One group of cylinders may be selectively disabled by cutting off its fuel supply while continuing to receive air. The exhaust system includes an NOx trap (20) to store NOx gases while the exhaust gases contain excess air. During part load operation, the engine is run with one group of cylinders disabled most of the time during which NOx gases are stored in the NOx trap (20). In order to permit the trap (20) to be regenerated or purged periodically, both group are fired at the same time for short intervals to supply a stoichiometric or reducing mixture to the exhaust system.

Patent
16 Jan 1996
TL;DR: In this article, a hybrid powertrain for an automotive vehicle comprising an internal combustion engine and transmission assembly providing a first selectably shiftable geared torque flow path to vehicle traction wheels and an electric motor-generator unit defining a second geared torqueflow path that is located between the output of the first geared flow path and the traction wheels.
Abstract: A hybrid powertrain for an automotive vehicle comprising an internal combustion engine and transmission assembly providing a first selectably shiftable geared torque flow path to vehicle traction wheels and an electric motor-generator unit defining a second geared torque flow path that is located between the output of the first geared torque flow path and the traction wheels. Through the deployment of an appropriate control system, including the necessary control algorithms, the electric motor-generator unit can be operated to supply torque to the traction wheels while the torque flow in the first torque flow path is interrupted during the occurrence of a ratio change in the transmission assembly and during disengagement of a clutch. Because of this interactive control of two power sources, the vehicle driveability can be enhanced along with an improvement of the engine exhaust gas emissions. In addition, the electric motor-generator unit in the second torque flow path can be used to launch the vehicle electrically immediately upon request of the operator. This ability of the powertrain permits engine-off operation during vehicle coast-down and standstill periods without any loss of driveability. During electric launch of the vehicle, the interactive control of the two power sources permits the internal combustion engine to be restarted and then gradually take over the propulsion task from the electric motor-generator unit.

Journal ArticleDOI
TL;DR: LBW was associated with ADHD but not with childhood anxiety disorders or oppositional defiant disorder, and the association was stronger in the urban than in the suburban population.
Abstract: The study examined the association between low birth weight (LBW) (≤2,500 g) and attention deficit hyperactivity disorder (ADHD) in two socioeconomically disparate populations. LBW and normal birth weight (NBW) children from the 1983 to 1985 newborn lists of an urban and a suburban hospital in Southeast Michigan were randomly selected. A total of 823 children, 473 LBW and 350 NBW, participated. Data were gathered in 1990 to 1992, when the children were 6 to 7 years of age. The National Institute of Mental Health Diagnostic Interview Schedule for children—Parent version (DISC-P) was used to elicit information on DSM-III-R diagnoses of simple phobia, overanxious, separation anxiety, oppositional defiant, and ADHD. Teachers' ratings of behavior problems were obtained. LBW was associated with ADHD but not with childhood anxiety disorders or oppositional defiant disorder. The association was stronger in the urban than in the suburban population. Data from teachers' ratings revealed an association between LBW and attention problems. The prognostic significance of the observed psychopathology at 6 years of age requires follow-up assessment as the children mature.

Journal ArticleDOI
TL;DR: In this paper, 25 commercially available silver-filled epoxies were evaluated for joint resistance stability on copper and tin/lead surface finishes after 500 h of 85/spl deg/C/85% RH aging.
Abstract: Electrically conductive adhesives offer a lead free, relatively low temperature process for attachment of surface mount components to printed circuit boards (PCB's). The National Center for Manufacturing Sciences (NCMS) Conductive Adhesives project has defined a requirement for an isotropically conductive adhesive (ICA). In this study, 25 commercially available silver-filled epoxies were evaluated for joint resistance stability on copper and tin/lead surface finishes after 500 h of 85/spl deg/C/85% RH aging. Mechanical properties were evaluated through lap shear and impact testing. This testing led to a set of requirements for a surface mount adhesive including a volume resistivity of 1 m/spl Omega/-cm, less than a 20% shift in resistance after aging, and the ability to pass six drops with a plastic leaded chip carrier (PLCC) 44 package from a height of 1.52 m (60 in). Promising candidate adhesives identified in the screening study were evaluated on a circuit board test vehicle with a variety of components. Assembly revealed a narrow processing window when compared to solder. Impact testing demonstrated that current materials have inadequate impact strength for many components and accelerated T/H aging reveals unstable electrical resistance with Sn/Pb finished components. Preliminary data is included on a new adhesive formulation that has been developed to address the shortcomings of currently available ICAs.

Journal ArticleDOI
TL;DR: Examining the relationship between low birth weight (LBW) and specific neurocognitive abilities at 6 years of age in a large-scale nonconcurrent prospective study revealed that test performance varied within birth weight levels and that performance continued to improve with increased birth weight well above 3000 g.

Patent
06 Sep 1996
TL;DR: In this article, a haptic interface between a user held physical device and a computer generated parametric surface determines if a collision has occurred there between the two points of contact, where the physical device is capable of transmitting forces in at least three degrees of freedom via the force actuation mechanism which is connected thereto.
Abstract: A method for providing a haptic interface between a user held physical device and a computer generated parametric surface determines if a collision has occurred therebetween. If a collision has occurred, a force to apply to the physical device is determined and a force actuation mechanism is activated so as to produce the force at the physical device. If a collision has not occurred, the force actuation mechanism is deactivated. The method is repeated as the physical device is moved through a virtual space in which the parametric surface is modeled. The physical device is capable of transmitting forces in at least three degrees-of-freedom via the force actuation mechanism which is connected thereto. A human operator holding the physical device can thus interact with the surface, which may be a CAD generated surface.