Lehigh University

About: Lehigh University is a education organization based out in Bethlehem, Pennsylvania, United States. It is known for research contribution in the topics: Catalysis & Fracture mechanics. The organization has 12684 authors who have published 26550 publications receiving 770061 citations.

Level control in the steam generator of a nuclear power plant

Abstract: Poor control of the steam generator water level in the secondary circuit of a nuclear power plant can lead to frequent reactor shutdowns. Such shutdowns are caused by violation of safety limits on the water level and are common at low operating power where the plant exhibits strong nonminimum phase characteristics and flow measurements are unreliable. There is, therefore, a need to systematically investigate the problem of controlling the water level in the steam generator in order to prevent such costly reactor shutdowns. The paper presents a framework for addressing this problem based on an extension of the standard linear model predictive control algorithm to linear parameter varying systems.

Behavioral momentum in the treatment of escape-motivated stereotypy.

Abstract: Descriptive and experimental analyses of stereotypy by a woman with severe mental retardation showed that the behavior was maintained by escape from demands. A sequence of high-probability requests issued immediately prior to a task-related request established a momentum of compliance that increased compliance with task-related demands. Increases in compliance were accompanied by collateral reductions in stereotypic behavior. A mechanism of response covariation, called functional incompatibility, and an animal analogue study for testing the validity of this mechanism are proposed.

CH4 conversion to value added products: Potential, limitations and extensions of a single step heterogeneous catalysis

Abstract: Natural gas is envisioned as a primary source of energy and hydrocarbons in the foreseeable future. Though shale gas has recently become abundant, it has two main concerns: its environmental impact and sustainable utilization. The former is the result of recent reports of natural gas emissions and flares into the environment, where it acts as a powerful greenhouse gas, whereas the latter is dictated by the need for efficient hydrocarbon utilization. Modern natural gas processing units that yield clean fuels and feedstock from methane, CH 4 , require extremely large capital investments and are not economical in remote natural gas extraction sites. Single step (direct), non-syngas based catalytic routes of CH 4 conversion to value added products have not been competitive economically and need to be reevaluated in the light of shale gas availability. This perspective discusses general considerations for the desired hydrocarbon products, the thermodynamic limitations involved in a single step conversion of CH 4 and heterogeneous catalytic routes based on high temperatures and oxide based catalysts. We then discuss other catalysts and methods of CH 4 activation that have recently emerged and are conceptually different from metal oxide catalyst based routes, such as those using sulfur or halogens. Lastly, we discuss a possible route of CH 4 monetization beyond the first reactive product (such as ethylene oligomerization into fuels), as well as currently explored photo(electro)chemical routes of CH 4 activation.

Design considerations in scaled SONOS nonvolatile memory devices

Abstract: Scaling the programming voltage, while still maintaining 10-year data retention time, has always been a big challenge for polysilicon–oxide–nitride–oxide–silicon (SONOS) researchers. We describe progress in the design and scaling of SONOS nonvolatile memory devices. We have realized −9+10 V (1 ms) programmable SONOS devices ensuring 10-year retention time after 107 erase/write cycles at 85°C. Deuterium anneals, applied in SONOS device fabrication for the first time, improves the endurance characteristics when compared with traditional hydrogen or forming gas anneals. We introduce scaling considerations and process optimization along with experiments and SONOS device characterization. A field programmable gate array-based measurement system is described for the dynamic characterization of SONOS nonvolatile memory devices.