Design of a multivariable integrated control for a supersonic propulsion system

An inlet/engine/nozzle integrated control mode for the propulsion system of an advanced supersonic commercial aircraft was studied. Results show that integration of these control functions can result in both operational and performance benefits for the propulsion system. For example, this integrated control mode may make it possible to minimize the use of inlet bypass doors for shock position control. This may be of benefit to the aircraft as a result of minimizing: (1) bypass bleed drag effects; (2) perturbations to the aircraft resulting from the side thrust effect of the bypass bleeds; and (3) potential unstarts of the inlet. A conceptual integrated control mode was developed which makes use of many cross coupling paths between inlet and engine control variables and inlet and engine sensed variables. A multivariable control design technique based upon linear quadratic regulator theory was applied to designing the feedback gains for this control to allow a simulation evaluation of the benefits of the integrated control mode

Preliminary study, analysis and design for a power switch for digital engine actuators

Innovative control configurations using high temperature switches to operate actuator driving solenoids were studied. The impact on engine control system life cycle costs and reliability of electronic control and (ECU) heat dissipation due to power conditioning and interface drivers were addressed. Various power supply and actuation schemes were investigated, including optical signal transmission and electronics on the actuator, engine driven alternator, and inside the ECU. The use of a switching shunt power conditioner results in the most significant decrease in heat dissipation within the ECU. No overall control system reliability improvement is projected by the use of remote high temperature switches for solenoid drivers

Identification of Volatile Compounds Produced by Brevibacterium Linens that Inhibit Molds

Mold contamination of processed food and its raw ingredients is a major concern in agriculture. Although at one time mold contamination of cheese and other foods was considered to be of little conse9uence, discovery of carcinogenic and/or teratogenic toxins (73) produced by molds commonly associated with food has changed this innocuous and frequent inconvenience into a serious health consideration. The presence of mold on or in cheese is a common occurrence, indeed, many cheeses depend upon molds to provide characteristic cheese flavor and texture. Cheeses such as blue, Roquefort, Camembert, and Brie are ripened under controlled conditions by species of Penicillium. While certain molds are desirable, adventitious molds are undesirable contaminants in manufacture of most cheeses. Long ripening periods at controlled temperatures and humidity favor the growth of adventitious molds on Cheddar and other hard cheeses. Control of molds in ripening rooms and throughout cheese manufacture is important. One mold colony can give rise to thousands of airborne spores which can contaminate many kilograms of cheese. Some of the molds isolated from cheese produce mycotoxins in the cheese (10, 11, 48); therefore, control of mold growth is of paramount importance for the cheese industry. Surface-ripened cheeses are ripened by a smear of bacteria and yeasts growing on the surface of the cheese. Brevibacterium linens, the predominant microorganism in the smear of surface-ripened cheeses, is responsible for the typical aroma and flavor of Limburger, Trappist, Brick, and similar cheeses (1, 5, 8, 41, 42, 43, 60, 84). The aroma of these cheeses is a well-known characteristic and is due to the proteolytic metabolism of microorganisms in the surface smear (1, 2, 13, 21, 22, 23, 24, 26, 81, 84, 85). An interesting aspect of surface-ripened cheeses noted by Grecz et al. (29) is resistance to spoilage by bacteria or molds. These workers found that extracts of surface-ripened cheeses and of B.linens produced similar antimicrobial activity (30, 31). Grecz et al. did not examine the aroma of surface-ripened cheeses for antimicrobial activity. The aromas of surface-ripened cheeses contain a variety of compounds, several of these compounds are inhibitory to mold growth in environments other than cheese. The purpose of research presented in this thesis was to evaluate volatile compounds produced by B. linens for antimycotic activity. A method was developed to quantify inhibition of mold growth and spore germination in the presence of B. linens. The identity of the inhibitory compound was determined. Furthermore, the concentration of the inhibitory compound necessary to inhibit spore germination was determined. This thesis is arranged in an alternative style. The comprehensive literature review is followed by two journal articles which describe the majority of materials and methods. Results and discussion are also included in the journal articles. Materials and methods or results not presented in an article are placed in appendices as are statistical information and raw data. The conclusions derived from the project are included as a separate section

Survival of the Goss’s Wilt Bacterium and Management Implications

Goss’s wilt is caused by the bacterium Clavibacter michiganensis subsp. nebraskensis (Cmn). The survival of Cmn in soil and crop residues was examined by Schuster (1975). Pure cultures of the bacterium in soil did not survive for long (less than two weeks), however the bacterium was able to survive for up to 10 months in infested surface crop residue. When the crop residue (leaves, stalks, cobs and ears) was buried at 4 inches or 8 inches, the bacterium was only detected in stalks residue after 10 months. Thus, conservation tillage practices that partially bury infested crop residue should reduce survival of the Goss’s wilt bacterium. Any tillage done must take into account soil conservation. Rotating to a non-host crop, such as soybean, will allow time for infested residues to breakdown and inoculum levels to decrease

Bacterial wilt symptoms are impacted by host age and involve net downward movement of Erwinia tracheiphila in muskmelon

Cucurbit bacterial wilt, caused by Erwinia tracheiphila, is a damaging disease of cucurbit crops in the Midwest and Northeast U.S. Current management of bacterial wilt relies primarily on insecticide applications to control striped and spotted cucumber beetles (Acalymma vittatum and Diabrotica undecimpunctata howardi, respectively), which vector E. tracheiphila. Development of alternative management strategies is constrained by a lack of understanding of bacterial wilt etiology. The impact of host age on rate on symptom development and extent of bacterial movement in the xylem of muskmelon (Cucumis melo cv. Athena) was evaluated following wound inoculation of 2- to 8-week-old plants in growth chamber experiments. Wilting occurred more rapidly in plants after inoculating E. tracheiphila into 2- or 4-week-old plants than 6- or 8-week-old plants. Recovery of viable cells from stem segments revealed that vascular spread of E. tracheiphila was more extensive below than above the inoculation point. These findings provide experimental evidence that host age impacts the rate of symptom development in cucurbit bacterial wilt and that movement of the xylem-inhabiting pathogen E. tracheiphila within muskmelon plants occurs primarily in the downward direction

Sensor failure detection system

Advanced concepts for detecting, isolating, and accommodating sensor failures were studied to determine their applicability to the gas turbine control problem. Five concepts were formulated based upon such techniques as Kalman filters and a screening process led to the selection of one advanced concept for further evaluation. The selected advanced concept uses a Kalman filter to generate residuals, a weighted sum square residuals technique to detect soft failures, likelihood ratio testing of a bank of Kalman filters for isolation, and reconfiguring of the normal mode Kalman filter by eliminating the failed input to accommodate the failure. The advanced concept was compared to a baseline parameter synthesis technique. The advanced concept was shown to be a viable concept for detecting, isolating, and accommodating sensor failures for the gas turbine applications

Sensor failure detection for jet engines

Revisions to the advanced sensor failure detection, isolation, and accommodation (DIA) algorithm, developed under the sensor failure detection system program were studied to eliminate the steady state errors due to estimation filter biases. Three algorithm revisions were formulated and one revision for detailed evaluation was chosen. The selected version modifies the DIA algorithm to feedback the actual sensor outputs to the integral portion of the control for the nofailure case. In case of a failure, the estimates of the failed sensor output is fed back to the integral portion. The estimator outputs are fed back to the linear regulator portion of the control all the time. The revised algorithm is evaluated and compared to the baseline algorithm developed previously

Oxidative Heck desymmetrisation of 2,2-disubstituted cyclopentene-1,3-diones

Oxidative Heck couplings have been successfully developed for 2,2-disubstituted cyclopentene-1,3-diones. The direct coupling onto the 2,2-disubstituted cyclopentene-1,3-dione core provides a novel expedient way of enantioselectively desymmetrising all-carbon quaternary centres