Showing papers by "Ford Motor Company published in 1994"

Neurocontrol of nonlinear dynamical systems with Kalman filter trained recurrent networks

Abstract: Although the potential of the powerful mapping and representational capabilities of recurrent network architectures is generally recognized by the neural network research community, recurrent neural networks have not been widely used for the control of nonlinear dynamical systems, possibly due to the relative ineffectiveness of simple gradient descent training algorithms. Developments in the use of parameter-based extended Kalman filter algorithms for training recurrent networks may provide a mechanism by which these architectures will prove to be of practical value. This paper presents a decoupled extended Kalman filter (DEKF) algorithm for training of recurrent networks with special emphasis on application to control problems. We demonstrate in simulation the application of the DEKF algorithm to a series of example control problems ranging from the well-known cart-pole and bioreactor benchmark problems to an automotive subsystem, engine idle speed control. These simulations suggest that recurrent controller networks trained by Kalman filter methods can combine the traditional features of state-space controllers and observers in a homogeneous architecture for nonlinear dynamical systems, while simultaneously exhibiting less sensitivity than do purely feedforward controller networks to changes in plant parameters and measurement noise. >

Why Rhodium in Automotive Three-Way Catalysts?

Abstract: The catalytic treatment of motor vehicle exhaust gas has been a feature of all passenger cars in the USA since the 1975 model year. It has since been adopted in all the developed countries as the principal means of con-trolling the emissions from vehicles powered by Otto-cycle internal com-bustion engines. These include passenger cars, light trucks, and heavy-duty trucks. Catalysts have been developed for motorcycles and even smaller power plants. The so-called three-way catalyst (TWC) has been in use since the 1979 model year. The name reflects the simultaneous treatment by this catalyst of the two reducing pollutants, carbon monoxide and uncombusted hydrocarbons, and the oxidizing pollutant, oxides of nitrogen.

Point mutation within the tyrosine kinase domain of the RET proto-oncogene in multiple endocrine neoplasia type 2B and related sporadic tumours

Abstract: The susceptibility loci for the three multiple endocrine neoplasia (MEN) type 2 syndromes have been mapped to the region of chromosome 10q11.2 containing the RET proto-oncogene, which codes for a receptor tyrosine kinase. The majority of MEN 2A and familial medullary thyroid carcinoma results from missense mutations within one of five cysteine codons in the extracellular domain of the RET proto-oncogene. We now report a missense mutation, resulting in the substitution of a threonine for a methionine at codon 918 in the tyrosine kinase catalytic domain, in the germline of 26 of 28 apparently distinct families with MEN 2B. DNA from five of 13 apparently sporadic MTC and one of 12 apparently sporadic phaeochromocytomas harboured a similar mutation, but the corresponding germline DNA was wildtype in each case.

Anti‐ICAM‐1 antibody reduces ischemic cell damage after transient middle cerebral artery occlusion in the rat

Abstract: Intercellular adhesion molecule-1 (ICAM-1) is a glycoprotein expressed on endothelial cells that facilitates leukocyte adhesion. To test the hypothesis that reduction of leukocytes in an ischemic lesion reduces ischemic brain damage, we measured the effect of administration of an anti-ICAM-1 monoclonal antibody on ischemic brain damage after transient middle cerebral artery occlusion in the rat. ICAM-1 expression increased in the ischemic lesion, and the lesion volume was significantly reduced by 41% in the anti-ICAM-1 antibody group compared with the control group (p < 0.05). Numbers of polymorphonuclear leukocytes (PMNs) were significantly reduced in the cortices of the anti-ICAM-1 antibody group compared with the control animals (p < 0.05). Our data indicate that administration of anti-ICAM-1 antibody results in a significant reduction of ischemic brain damage concomitant with a reduction of PMNs in the lesion after transient focal cerebral ischemia in the rat.

Migraine and Major Depression: A Longitudinal Study

Abstract: SYNOPSIS Recent epidemiologic studies have reported an association between migraine and major depression. Little is known about the mechanisms that link the two disorders, or the natural history of their co-occurrence. We examined the association between migraine and major depression in a sample of young adults, using longitudinal data. Method: A random sample of 1,007 young adults (21–30 years of age) members of a large HMO in Southeast Michigan was interviewed in 1989; 97% of the sample were reinter-viewed 3.5 years later, in 1992. A structured diagnostic interview was used to elicit information on DSM-III-R major depression and IHS migraine in lifetime (in the 1989 interview) and during the 3.5 year follow-up interval (in the 1992 interview). Using Cox-proportional hazards models with time-dependent covariates, we estimated the relative risk for major depression associated with prior migraine and the relative risk for migraine associated with prior major depression. Results: In this sample of young adults, the incidence of migraine per 1,000 person years, based on the prospectively gathered data, was 5.0 in males and 22.0 in females. The estimated relative risk for major depression associated with prior migraine, adjusted for sex and education, was 3.2 (95% CI 2.3–4.6). The adjusted relative risk for migraine associated with prior major depression was 3.1 (95% CI 2.0–5.0). Conclusions: The study provides the first body of evidence that the previously observed cross-sectional association between migraine and major depression can result from bidirectional influences, with each disorder increasing the risk for first onset of the other. The explanation that major depression in persons with migraine represents a psychologic response to migraine attacks would have been more plausible had we found an influence only from migraine to depression. By diminishing the plausibility of a simple causal explanation for the migraine-depression comorbidity, the findings favor the shared mechanisms explanation.

Stability of linear feedback systems with random communication delays

Abstract: Integral control of large-scale systems implies coordination of activities by information exchange via communication networks. Usually these networks are shared with other users. Thus traffic conditions in the network may introduce time-varying random delays in the control loop with adverse effects on its performance and stability. Hence, the control must be designed to compensate for these delays. Recent work in modelling integrated control and communication systems has shown that the communication specific phenomena inducing random communication delays (such as multirate sampling, vacant sampling and message rejection) may be encompassed by finite-dimensional linear discrete-time models, provided that the plant and the controller are linear and time invariant. Existing approaches to the design of integrated control systems rely on conservative stability tests, because only sufficient stability conditions were found for systems with random time-varying delays. In this paper, necessary and sufficient cond...

Electronic control system

Abstract: A standardized microcontroller-based fuzzy logic processing module (101) for generating control signal values in response to variable input signal values in accordance with constraints imposed by propositions or "rules" stored in memory (117) in a standardized format. Each rule consists of one or more input conditions and an output directive. Each input signal (110) and the output signal (112) values are characterisable by their degree of membership in a predetermined number of fuzzy sets, each fuzzy set being defined by a membership function (119). Each input condition is composed of a reference to a particular input variable, which has been preprocessed into integer (whole number) normalised form and a reference to a membership function. Each output directive includes a reference to a further membership function. Each membership function is implemented by one of a three possible forms of standard membership data structures: a triangular function represented by three data points, a table lookup function represented by a two end data points and the points between these two end points, and an standard shape function composed of a set of data points and a set of reference points used to form a similar shape function by interpolation. Fuzzy logic processing is accomplished by determining the extent to which the input conditions are satisfied by the current values of the input signals in order to develop a rule strength value, and then performing a "centre-of-gravity" determination based on the output membership function values (118) of each satisfied rule integrated over the range of possible output signal values.

Nocardial Brain Abscess: Treatment Strategies and Factors Influencing Outcome

Abstract: The successful management of nocardial brain abscess remains problematic. The authors report 11 cases of nocardial brain abscess treated between 1971 and 1993 and review 120 cases reported since 1950. The clinical findings included focal deficits in 55 patients (42%), nonfocal findings in 36 (27%), and seizures in 39 (30%). Extraneural nocardiae were present in 66% of the cases; pulmonary (38%) and cutaneous/subcutaneous (20%) locations were the most frequent. The abscesses were single in 54% of the patients, multiple in 38%, and of unknown number in 8%. Forty-four of 131 patients (34%) were immunocompromised; since 1975, 18 of 40 immunocompromised patients (45%) were transplant recipients and six (15%) had human immunodeficiency virus. The mortality rate was 24% after initial craniotomy and excision (11/45), 50% after aspiration/drainage (17/34), and 30% after nonoperative therapy (7/23); 29 cases (22%) were diagnosed at autopsy. The mortality rate was 33% in patients with single abscesses and 66% in those with multiple abscesses (P < 0.0003). There was no difference in the mortality rates of immunocompromised and nonimmunocompromised patients treated before computed tomography (CT) was available; since the advent of CT, however, the mortality rate has been significantly higher in immunocompromised patients (55% vs. 20%, P < 0.05). Although the mortality rate for nocardial brain abscesses has dropped almost 50% since the advent of CT, it has remained virtually unchanged in immunocompromised patients and is three times higher than that of other bacterial brain abscesses (30% vs. 10%). The authors recommend image-directed stereotactic aspiration for diagnosis; however, craniotomy and total excision are necessary in most cases, because nocardial abscesses are usually multiloculated. Patients with minimal neurological deficits or small abscesses may be treated initially with antibiotics alone. Sulfonamides, alone or in combination with trimethoprim, are most effective and should be continued for at least 1 year. Minocycline, imipenem, or aminoglycoside in combination with a third-generation cephalosporin may be used with reasonably good success as second-line agents in cases of allergy or nonresponsiveness to sulfa agents.

Cathepsin B Expression and Localization in Glioma Progression and Invasion

Abstract: The poor prognosis of human malignant gliomas is due to their invasion and recurrence, the molecular mechanisms of which remain poorly characterized. We have accumulated substantial evidence implicating the cysteine protease cathepsin B in human glioma malignancy. Increases in cathepsin B expression were observed throughout progression. In primary brain tumor tissue, transcript abundance (Northern blot analysis) increased in low-grade astrocytoma to high-grade glioblastoma from 3- to 6-fold, respectively, above normal brain levels. This increase correlated with increases in protein abundance (from + to ) as measured by immunohistochemistry. Furthermore, in glioblastoma cell lines increases in transcript abundance (ranging from 3- to 12-fold) were accompanied by increases in enzyme activity (44-133 nmol/min x mg protein). Altered subcellular localization was observed both immunohistochemically and by indirect immunofluorescence confocal microscopy and was found to correlate with increased grade. In addition, this increase in cathepsin B expression and altered subcellular localization correlated with histomorphological invasion and clinical evidence of invasion as detected by magnetic resonance imaging. These data support the hypothesis that cathepsin B plays a role in human glioma progression and invasion.

Effects of long-term monotherapy with enalapril, metoprolol, and digoxin on the progression of left ventricular dysfunction and dilation in dogs with reduced ejection fraction.

Abstract: BACKGROUNDRecent clinical trials have suggested that therapy with angiotensin-converting enzyme inhibitors in asymptomatic patients with reduced left ventricular (LV) function can significantly reduce the incidence of congestive heart failure compared with patients receiving placebo. In the present study, we examined the effects of long-term monotherapy with enalapril, metoprolol, and digoxin on the progression of LV systolic dysfunction and LV chamber enlargement in dogs with reduced LV ejection fraction (EF).METHODS AND RESULTSLV dysfunction was produced in 28 dogs by multiple sequential intracoronary microembolizations. Embolizations were discontinued when LVEF was 30% to 40%. Three weeks after the last embolization, dogs were randomized to 3 months of oral therapy with enalapril (10 mg twice daily, n = 7), metoprolol (25 mg twice daily, n = 7), digoxin (0.25 mg once daily, n = 7), or no treatment (control, n = 7). As expected, in untreated dogs, LVEF decreased (36 +/- 1% versus 26 +/- 1%, P < .001) an...

DSM-III-R nicotine dependence in young adults: prevalence, correlates and associated psychiatric disorders.

Abstract: We describe the epidemiology of nicotine dependence and its association with other substance use and psychiatric disorders. Data came from a random sample of young adults, 21-30 years of age, in the Detroit, Michigan metropolitan area. The NIMH Diagnostic Interview Schedule was used to ascertain DSM-III-R disorders. Lifetime prevalence of nicotine dependence was 20%. Higher rates were observed in whites, persons with low education and persons who were separated or divorced. Males and females with nicotine dependence had significantly increased odds for alcohol and illicit drug disorders, major depression and one or more anxiety disorder, as compared to non-dependent smokers and non-smokers combined. Among smokers, lifetime prevalence of illicit drug disorders other than marijuana alone, major depression and any anxiety disorder were significantly higher in dependent than non-dependent people. Major depression was associated specifically with nicotine dependence, an association explained in part by neuroticism. This finding suggests that the personality trait of neuroticism might constitute a common predisposition for major depression and nicotine dependence.

Representation of geometric variations using matrix transforms for statistical tolerance analysis in assemblies

Abstract: The goal of this article is to develop a tolerance representation for assemblies compatible with tolerance analysis based on a closed-form algorithm used in robotic applications. A methodology is described that represents standard Y14.5M-1982 tolerances using homogeneous 4×4 matrix transforms. Transforms represent both the nominal relations between parts and the variations caused by geometric deviations allowed by the tolerances. The analysis calculates a statistical estimate of the location of theNth part in an assembly starting from the first part or a fixture. Except forform tolerances, most types of tolerance specifications are compatible with the proposed representation. This approach is well suited to integration with CAD systems and feature-based design. Since assembly apparatus errors can be calculated using the same methodology, one can predict the relative position and angle errors between two parts about to be mated. This permits useful evaluation of assembly equipment errors, comparison of different product tolerance assignments, and calculations of assembly process capability.

Algorithms for fully automated three-dimensional particle tracking velocimetry

Abstract: A three-dimensional Particle Tracking Velocimetry (3-D PTV) technique has been developed to provide time-resolved, three-dimensional velocity field measurements throughout a finite volume. This technique offers many advantages for fundamental research in turbulence and applied research in areas such as mixing and combustion. The data acquired in 3-D PTV is a time sequence of stereo images of flow tracer particles suspended in the fluid. In this paper, the implementation of the technique is discussed in detail, as well as the results of an extensive statistical investigation of the performance of the algorithms. The technique has been optimized to allow fully automatic processing of long sequences of image pairs in a computationally efficient manner, hereby providing a viable, practical tool for the study of complex flows.

Prophylaxis for Stress-related Gastric Hemorrhage in the Medical Intensive Care Unit: A Randomized, Controlled, Single-Blind Study

Abstract: OBJECTIVE To determine the efficacy and safety of cimetidine and sucralfate prophylaxis for stress-related gastrointestinal hemorrhage in patients admitted to a medical intensive care unit. SETTING Medical intensive care unit of a nonprofit, university-affiliated teaching hospital. PATIENTS 300 patients admitted to the medical intensive care unit during a 10-month period. DESIGN Randomized, controlled, single-blind clinical trial. INTERVENTION Patients were assigned to receive no prophylaxis (control), 1 g sucralfate given orally every 6 hours, or continuous intravenous cimetidine titrated to maintain gastric pH at 4.0, intervention was maintained until the occurrence of clinically severe hemorrhage, onset of drug-related complications, death, or discharge from the medical intensive care unit. OUTCOME MEASURES The primary outcome measure was the incidence of clinically severe hemorrhage from endoscopically verified stress-related gastritis. Other outcome measures were transfusion requirements, duration of medical intensive care unit stay, incidence of nosocomial pneumonia, adverse drug reactions, and death. RESULTS 100 patients were randomly assigned to each treatment. The three groups were similar with regard to demographic characteristics, intensive care unit admission diagnoses, and APACHE II scores. Stress-related hemorrhage was seen in 6% of control participants and in 5% of those receiving sucralfate or cimetidine (relative risk compared with control, 0.83 for each group; 95% CI, 0.26 to 2.64; P = 0.75). No statistically significant differences were found for transfusion requirements, duration of medical intensive care unit stay, and mortality rates among the three groups. Nosocomial pneumonia was diagnosed in 6%, 12%, and 13% of controls, sucralfate recipients, and cimetidine recipients, respectively (sucralfate: relative risk, 2.0 [CI, 0.79 to 5.01], P = 0.14; cimetidine: relative risk, 2.2 [CI, 0.88 to 5.33], P = 0.09). Prophylaxis caused no definite adverse drug reactions. CONCLUSIONS The observed effects of cimetidine and sucralfate on the incidence and severity of hemorrhage from stress-related gastritis were not significant when compared with no treatment. Routine prophylaxis with these agents for patients entering the medical intensive care unit does not seem warranted.

Control system and method utilizing generic modules

Abstract: A control system and method for motor vehicles uses generic control modules which communicate over a vehicle trunkline to accommodate applications of varying functional content and complexity The vehicle trunkline provides power distribution and a number of communication channels for the various generic control modules which include controller modules, interface modules, and combination controller/interface modules Each generic control module is connected to the vehicle trunkline via a standardized connector The combination modules and interface modules are connected to system actuators and sensors with relatively short, simple overlay wiring The system allows distributed computation for the control of functions and utilizes communication networks to reduce the number of conductors required while increasing the utilization of processing capabilities

A gradient relationship between low birth weight and IQ at age 6 years.

Abstract: Objective: To test for a suspected adverse effect of low birth weight (≤2500 g) on IQ at age 6 years in two socioeconomically disparate populations. Design: Nonconcurrent prospective study. Setting: An urban, predominantly disadvantaged population and a suburban middle-class population in southeastern Michigan. Participants: Low-birth-weight (N=473) and normal-birth-weight (N=350) subjects, randomly selected from the 1983 through the 1985 newborn lists of two major hospitals, one serving an urban and the other a suburban population. Main Outcome Measure: The Wechsler Intelligence Scale for Children–Revised to measure IQ. Results: The mean full-scale IQ of low-birth-weight children was 4.9 points lower than that of normal-birth-weight children, controlling for population site, maternal IQ, maternal education, and race (95% confidence interval [CI], 3.0 to 6.8). There was no evidence of low-birth-weight interaction with population site, and the same IQ difference was detected in both populations. In the urban population, low birth weight was associated with an increased risk for IQ below 85 (odds ratio, 2.2; 95% CI, 1.3 to 3.7). In the suburban population, low birth weight was associated with an increased risk for IQ below 100 (odds ratio, 2.0; 95% CI, 1.2 to 3.4). A gradient relationship with full-scale IQ was observed, with the largest deficit in those born weighing 1500 g or less, an intermediate deficit in those born weighing 1501 through 2000 g, and the least pronounced deficit in those born weighing 2001 through 2500 g. Conclusions: The overall effect of low birth weight represents an increase of approximately 10% of low-birth-weight children with an IQ of more than 1 SD below the population's mean. Children born weighing 2000 g or less bore the major burden of the IQ deficits. (Arch Pediatr Adolesc Med. 1994;148:377-383)

Tensile behavior of a new single-crystal nickel-based superalloy (CMSX-4) at room and elevated temperatures

Abstract: Tensile behavior of a new single-crystal nickel-based superalloy with rhenium (CMSX-4) was studied at both room and elevated temperatures. The investigation also examined the influence of γ′ precipitates (size and distribution) on the tensile behavior of the material. Tensile specimens were prepared from single-crystal CMSX-4 in [001] orientation. The test specimens had the [001] growth direction parallel to the loading axis in tension. These specimens were given three different heat treatments to produce three different γ′ precipitate sizes and distributions. Tensile testing was carried out at both room and elevated temperatures. The results of the present investigation indicate that yield strength and ultimate tensile strength of this material initially increases with temperature, reaches a peak at around 800 °C, and then starts rapidly decreasing with rise in temperature. Both yield and tensile strength increased with increase in average γ′ precipitate size. Yield strength and temperature correlated very well by an Arrhenius type of relationship. Rate-controlling process for yielding at very high temperature (T ≥ 800 °C) was found to be the dislocation climb for all three differently heat-treated materials. Thermally activated hardening occurs below 800 °C whereas above 800 °C thermally activated softening occurs in this material.

Method and apparatus to limit a midbed temperature of a catalytic converter

Abstract: An electronic engine controller limits the maximum temperature of a midbed point within a catalytic converter by determining an instantaneous temperature of the midbed point as a function of a temperature of exhaust gas at an exhaust flange, of a temperature variation of exhaust gas from the exhaust flange and exhaust gas inlet to the catalytic converter, of exhaust gas at an exhaust gas inlet to the catalytic converter, and as a function of a predetermined value indicative of a temperature rise of exhaust gas in the catalytic converter. The temperature is compared to a maximum midbed temperature range and a first air/fuel modulation variable is altered by a predetermined amount if the temperature of the midbed point is within the maximum midbed temperature range and the first air/fuel modulation variable is set to a predetermined value if the midbed temperature is below the maximum midbed temperature range. The first air/fuel modulation variable is compared to a second air/fuel modulation variable which corresponds to an air/fuel ratio required to produce a predetermined engine response and the rate of fuel delivery to the engine is altered to generate an air/fuel ratio corresponding to the air/fuel modulation variable which represents the richer air/fuel mixture.

NO2 formation over Cu-ZSM-5 and the selective catalytic reduction of NO

Abstract: The extent of the selective catalytic reduction (SCR) of nitric oxide to dinitrogen in the presence of excess oxygen is enhanced by the oxygen on several zeolite-based catalysts and using different reductants. When the catalyst is Cu-ZSM-5 and the reductant is a hydrocarbon, an NO2 intermediate has been suggested by several investigators. This work shows that at short residence times, with excess reductant and in the absence of oxygen, the NO2 itself is reduced only back to NO. Thus, for the selective reduction of NO2 to N2 (N-pairing) strongly oxidizing conditions are required, same as for the complete reduction of NO. In the presence of excess oxygen the activity of Cu-ZSM-5 in the NO + O2 reaction to form NO2 parallels the SCR in every respect. It is higher over Cu-ZSM-5 than on Cu/Al2O3 or on H-ZSM-5. The coppercontaining zeolite is also active in the decomposition of NO2 back to NO and O2 while the other catalysts are much less active. The inhibiting effect of water on the NO + O2 catalytic reaction is also parallel to the effect on SCR. This evidence strengthens the notion of an NO2 intermediate.

System and method for processing test measurements collected from an internal combustion engine for diagnostic purposes

Abstract: A system and method for processing test measurements collected from an internal combustion engine that is cold-tested for diagnostic purposes. Test measurements are collected from an engine. The test measurements are "pre-processed" by filtering and subsampling techniques so that Principal Component Analysis can be applied to condense the quantity of test measurements while still retaining a statistically accurate indication of a majority of the original measurements. The pre-processed test measurements are then passed through one or more classifiers including: a Neural Network classifier, a Fuzzy Logic classifier, a cluster-based classifier (or "Spherical"classifier) and a Genetic Program classifier. Results from these classifiers canbe used to obtain a verdict about an engine (i.e., whether the engine is "normal" or "faulty").

Oxygen availability in mixed cerium/praseodymium oxides and the effect of noble metals

Abstract: Oxyreduction studies of mixed Ce/Pr oxides have been carried out. Temperature-programmed desorption (TPD), temperature-programmed reduction (TPR), and temperature-programmed oxidation (TPO) were used to study the uptake and release of the oxygen. Large amounts of oxygen, exceeding those in ceria, are accessible in the mixed metal oxides at moderate temperatures. The addition of small amounts of noble metals to the mixed oxides shifts the accessibility of the “stored” oxygen to still lower temperatures with the effect of Pd being more pronounced than that of Pt. In a sample containing 45 mol % ceria and 55 mol % praseodymia, a small addition of Pd (0.24 mol %) was found to lower the reduction temperature by more than 100 °C. The addition of Pt had a lesser effect. Similarly, in pure praseodymia (Pr6O11) Pd influences the reduction much more strongly than Pt. In the mixed samples, whether doped with a noble metal or not, the whole oxyreduction effect can be accounted for by the change in oxidation state of the praseodymium ions solely. This notwithstanding, the reduction of the mixed oxides, without noble metals or doped by Pt, is more facile than that of praseodymia. Only the incorporation of Pd makes the reduction of praseodymia proceed at a temperature below that registered for a mixed ceriapraseodymia sample.

Rotational response and slip prediction of serpentine belt drive systems

Abstract: A nonlinear model is developed which describes the rotational response of automotive serpentine belt drive systems. Serpentine drives utilize a single {long) belt to drive all engine accessories from the crankshaft. An equilibrium analysis leads to a closedform procedure for determining steady-state tensions in each belt span. The equations of motion are linearized about the equilibrium state and rotational mode vibration characteristics are determined from the eigenvalue problem governing free response. Numerical solutions of the nonlinear equations of motion indicate that, under certain engine operating conditions, the dynamic tension fluctuations may be sufficient to cause the belt to slip on particular accessory pulleys. Experimental measurements of dynamic response are in good agreement with theoretical results and confirm theoretical predictions of system vibration, tension fluctuations, and slip.

Air/fuel control with on-board emission measurement

Abstract: An engine air/fuel control system (8) and method for controlling an engine (28) coupled to a catalytic converter (50) and for providing a measurement of engine emissions (202-296). Nitrogen oxides concentration, hydrocarbon concentration, and carbon monoxide concentration of exhaust gases downstream of the converter are measured (46, 54, and 52). Each concentration measurement is averaged for the speed load cell in which such measurement occurred (244-256). Each concentration average measurement is converted to a measurement of mass emissions emitted during a test cycle (268-284). Fuel delivered to the engine is corrected by a feedback variable (104-134, 158-178) derived from both an exhaust gas oxygen sensor (44) positioned upstream of the converter and the three sensors positioned downstream of the converter (46, 52, 54). A measurement of emissions in response to the averaged mass measurements of emission concentration downstream of the converter is also provided (278-296).

Stability robustness of LQ and LQG active suspensions

Abstract: A two-degree-of-freedom quarter-car model is used as the basis for linear quadratic (LQ) and linear quadratic Gaussian (LQG) controller design,for an active suspension. The LQ controller results in the best rms performance trade-offs (as defined by the performance index) between ride, handling and packaging requirements. In practice, however, all suspension states are not directly measured, and a Kalman filter can be introduced,for state estimation to yield an LQG controller. This paper (i) quantifies the rms performance losses for LQG control as compared to LQ control, and (ii) compares the LQ and LQG active suspension designs,from the point of view of stability robustness