An interior penalty method for inequality constrained optimal control problems

This paper presents a penalty function approach to the solution of inequality constrained optimal control problems. The method begins with a point interior to the constraint set and approaches the optimum from within, by solving a sequence of problems with only terminal conditions as constraints. Thus, all intermediate solutions satisfy the inequality constraints. Conditions are given which guarantee that the un "constrained" problems have solutions interior to the constraint set and that in the limit these solutions converge to the constrained optimum. For linear systems with convex objective and concave inequalities, the unconstrained problems have the property that any local minimum is global. Further, under these conditions, upper and lower bounds in the optimum are easily available. Three test problems are solved and the results presented.     

Measurements of microwaves scattered from a moving density-modulated plasma

Measurements of the absolute intensity and the angular distribution of the microwaves scattered from an oscillating plasma column of a finite length are presented. These measurements show that the scattered wave produces diffraction patterns and frequency shifts. The results substantiate quantitatively the theory of nonlinear microwave scattering.     

Effect of histamine on technetium-99m excretion by gastric mucosa

The ability of histamine to increase excretion of 99mtechnetium by gastric mucosa was investigated in dogs with Heidenhain pouches and denervated antral pouches. Histamine increased Heidenhain pouch 99mtechnetium output in a dose-related manner, and 99mtechnetium output was related linearly to acid output. Antral pouch 99mtechnetium output was unchanged by increasing doses of histamine. The study suggests that concomitant use of histamine may improve the accuracy of 99mtechnetium scanning in the clinical diagnosis of conditions caused by ectopic gastric mucosa.     

Pneumomediastinum in heroin and marijuana users

During the past three years, more than 500 patients were seen with mediastinal or cervical emphysema or both the Ben Taub General Hospital Emergency Center. In all but 15 there was a history of recent trauma or antecedent respiratory conditions with repeated sustained intrabronchial pressure, such as asthma. These 15 patients had a common history of repeated sustained Valsalva's maneuvers during marijuana smoking or during intravenous injections of heroin. The results of esophagography, bronchoscopy, and esophagoscopy were normal in these 15 patients. Conservative management consisted of close observation and re-evaluation for possible causes of secondary pneumomediastinum. All recovered without sequelae with resolution of the pneumomediastinum within 2 to 5 days. Radiographic and physical findings in primary pneumomediastinum resulting from prolonged intraalveolar hyperpressure are similar to those seen in patients with trauma or spontaneous rupture of the esophagus.     

Orbital involvement by plasmacytoma. Report of two cases

Two patients with orbital involvement of plasma cell myeloma are presented. The first patient presented an isolated plasmacytoma in the orbit; the second patient had generalized plasma cell myeloma. In both cases X-rays and computed tomographic scanning gave valuable information and biopsy confirmed the diagnosis.     

Material transport phenomena in the impact wear of titanium alloys

Results are presented from compound impact wear studies performed with titanium alloys of different β phase content and morphology. The “material pair” consisted of a 17-4 PH stainless steel counterface and a flatended titanium alloy specimen. Each material pair was exposed to variations in relative transverse sliding velocity and number of repetitive load cycles. Testing was conducted primarily at a single level of nominal peak normal impulsive stress.Both optical and scanning electron microscopy were used to monitor changes in worn surface and subsurface regions. Energy-dispersive X-ray studies of the initial and worn surfaces comprising the material pair clearly indicated the nature of the material transport between the opposing surfaces. Wear debris were studied by optical microscopy and by powder X-ray techniques.Utilizing the reciprocating impact wear testing apparatus, it was determined that material transport appears to be a controlling factor. The type of transport (i.e. material passing from specimen to counterface or vice versa) was found to vary under differing test conditions. Such findings may contribute to the understanding of wear for systems other than those characterized by repetitive impulsive contact.Material removal is minimal at particular levels of relative transverse sliding velocity, and these levels are not necessarily affected by the magnitude of the nominal level of stress. It appears that the nature and quantity of the constituents (α, β) in the titanium alloys are critical in establishing wear behavior for the material pairs investigated.