Robust fixed order dynamic compensation for large space structure control

A simple formulation for designing fixed order dynamic compensators which are robust to both uncertainty at the plant input and structured uncertainty in the plant dynamics is presented. The emphasis is on designing low order compensators for systems of high order. The formulation is done in an output feedback setting which exploits an observer canonical form to represent the compensator dynamics. The formulation also precludes the use of direct feedback of the plant output. The main contribution lies in defining a method for penalizing the states of the plant and of the compensator, and for choosing the distribution on initial conditions so that the loop transfer matrix approximates that of a full state design. To improve robustness to parameter uncertainty, the formulation avoids the introduction of sensitivity states, which has led to complex formulations in earlier studies where only structured uncertainty has been considered

A hydrodynamic study of a fast‐bed dual circulating fluidized bed for chemical looping combustion

This study explores the use of a dual interconnected circulating fluidized bed (CFB) for chemical looping combustion. This design can enhance gas–solid interactions, but it is difficult to control the solid transfer and circulation rates. With the use of a 1:1 scale cold-flow model, an investigation determining the hydrodynamic behavior of the dual CFB system has been conducted. The cold-flow system consists of two identical fast-bed risers, each with an internal diameter of 100 mm and a height of 7 m. The simplified cold-flow model is based on the chemical looping Pilot-Scale Advanced CO2 Capture Technology (PACT) facility at Cranfield. Here, we have determined the minimum fluidization and transport velocities, and we have assessed the solid density profiles, transport capacity, and potential for the dilution by air/N2 leakage into the CO2 stream exiting the fuel reactor. The experimental procedure uses two different bed materials, molochite (ceramic clay) and FE100 (iron particles), and it satisfies the dynamic scaling laws to model the bed inventory within the system. The results indicate that the two fast-bed risers share similar density and pressure profiles. Stable circulation can be achieved through pneumatic transport. The circulation rate of the system is flexible and can be adjusted by altering the fluidization velocity in the riser and by altering the bed inventory. The gas leakage from the loop seal to the cyclone was found to be sensitive to the bed height and fluidization velocity in the loop seal. However, by maintaining a loop-seal bed height above 600 mm during operation, the outlet stream remains undiluted

Pressurised calcination-atmospheric carbonation of limestone for cyclic CO2 capture from flue gases

A study was carried out to investigate the CO2 capture performance of limestone under atmospheric carbonations following pressurised calcination. A series of tests was carried out to study the role of pressurised calcination using a fluidised bed reactor. In this investigation, calcination of limestone particles was carried out at three levels of pressure: 0.1 MPa, 0.5 MPa, and 1.0 MPa. After calcination, the capture performance of the calcined sorbent was tested at atmospheric pressure. As expected, the results indicate that the carbonation conversion of calcined sorbent decreases as the pressure is increased during calcination. Pressurised calcination requires higher temperatures and causes an increase in sorbent sintering, albeit that it would have the advantage of reducing equipment size as well as the compression energy necessary for CO2transport and storage, and an analysis has been provided to give an assessment of the potential benefits associated with such an option using process software.EPSR

Beyond Options

Scholars and policymakers now debate reforms that would prevent a bankruptcy filing from being a moment that forces valuation of the firm, crystallization of claims against it, and elimination of junior stakeholders’ interest in future appreciation in firm value. These reforms have many names, ranging from Relative Priority to Redemption Option Value. Much of the debate centers on the extent to which reform would protect the non-bankruptcy options of junior stakeholders, or harm the non-bankruptcy options of senior lenders. We argue that this focus on options misplaced. Protecting options is neither necessary nor sufficient for advancing the goal of a well-functioning bankruptcy system. What is needed is a regime that cashes out the rights of junior stakeholders with minimal judicial involvement. To illustrate, we propose an “automatic bankruptcy procedure” that gives senior creditors an option to restructure the firm’s debt or sell its assets at any time after a contractual default. Under this procedure, restructuring occurs in bankruptcy, but sales do not. Sales are either subject to warrants (which give junior stakeholders a claim on future appreciation) or are subject to judicial appraisal (which forces senior lenders to compensate junior stakeholders if the sale price was too low). Our proposal can be seen as an effort to design a formalized restructuring procedure that borrows from traditional state law governing corporate-control transactions. We show that this procedure minimizes core problems of current law – fire sales that harm junior stakeholders, delay that harms senior lenders, and the uncertainties generated by judicial valuation, which are exploited by all parties

Three Models of Legal Ethics

This article presents a picture of each of the three theoretical models—autonomy, socialist, and deontological—and indicates how they differ from one another in their application to some aspects of attorney-client confidentiality, one of the most hotly debated topics of professional ethics

Three Models of Legal Ethics

This article presents a picture of each of the three theoretical models—autonomy, socialist, and deontological—and indicates how they differ from one another in their application to some aspects of attorney-client confidentiality, one of the most hotly debated topics of professional ethics

Terminal Deoxynucleotidyl Transferase: The Story of A Misguided DNA Polymerase

Nearly every DNA polymerase characterized to date exclusively catalyzes the incorporation of mononucleotides into a growing primer using a DNA or RNA template as a guide to direct each incorporation event. There is, however, one unique DNA polymerase designated terminal deoxynucleotidyl transferase that performs DNA synthesis using only single-stranded DNA as the nucleic acid substrate. In this chapter, we review the biological role of this enigmatic DNA polymerase and the biochemical mechanism for its ability to perform DNA synthesis in the absence of a templating strand. We compare and contrast the molecular events for template-independent DNA synthesis catalyzed by terminal deoxynucleotidyl transferase with other well-characterized DNA polymerases that perform template-dependent synthesis. This includes a quantitative inspection of how terminal deoxynucleotidyl transferase binds DNA and dNTP substrates, the possible involvement of a conformational change that precedes phosphoryl transfer, and kinetic steps that are associated with the release of products. These enzymatic steps are discussed within the context of the available structures of terminal deoxynucleotidyl transferase in the presence of DNA or nucleotide substrate. In addition, we discuss the ability of proteins involved in replication and recombination to regulate the activity of the terminal deoxynucleotidyl transferase. Finally, the biomedical role of this specialized DNA polymerase is discussed focusing on its involvement in cancer development and its use in biomedical applications such as labeling DNA for detecting apoptosis

Partnering with Parents: Promising Approaches to Improve Reunification Outcomes for Children in Foster Care

Family reunification is one of the central tenents of the child welfare system, yet research supporting effective practices to promote safe reunifications is limited. As a departure from previous initiatives, the Parent Partner (PP) program enlists as staff mothers and fathers who have experienced child removal, services, and reunification. This study examines outcomes for children served by the PP program. The experimental group includes 236 children whose parents were served by a Parent Partner and a matched comparison group of 55 children whose parents were served by the public child welfare agency in 2004, before the Parent Partner program was established. Cases were examined 12 months following case opening to determine reunification status. Results from the outcome study indicate that reunification may be more likely for children whose parents were served by Parent Partners. Although there are limitations to the data, findings from this study suggest that the Parent Partner model may hold promise as a child welfare intervention designed to support reunification

Optimisation of a quasi-steady model of a free-piston Stirling engine

Energy from waste heat recovery is receiving considerable attention due to the demand for power systems that are less polluting. This has led to the investigation of external combustion engines such as the free-piston Stirling engine (FPSE) due to its ability to generate power from any source of heat and, especially, waste heat. However, there are still some limitations in the modelling, design and practical utilisation of this type of engine. Modelling of the FPSE has proved to be a difficult task due to the lack of mechanical linkages in its configuration, which poses problems for achieving stability. Also, a number of studies have been reported that attempt to optimise the output performance considering the characteristics of the engine configuration. In this study the optimisation of the second-order quasi-steady model of the gamma-type FPSE is carried out using the genetic algorithm (GA) to maximise the performance in terms of power output, and considering the design parameters of components such as piston and displacer damper, geometry of heat exchangers, and regenerator porosity. This present study shows that the GA optimisation of the RE-1000 FPSE design parameters improved its performance from work done and output power of 33.2 J and 996 W, respectively, with thermal efficiency of 23%, to 44.2 J and 1326 W with thermal efficiency of 27%

Trends in Cancer Mortality in 15 Industrialized Countries, 1969-1986

Background: Assessing trends in cancer provides a means for gauging progress against the disease, estimating future demands for care and treatment, and suggesting clues about shifting causal factors that may account for the more recent changes. Purpose: This study was designed to evaluate trends in the major sites of cancer associated with high mortality rates in 15 industrialized countries. To highlight differences among regions, we grouped these countries into six geographic areas: United States, Eastern Europe, Western Europe, East Asia, Oceania, and Nordic countries. In addition, cancer mortality trends in these regions were compared with incidence patterns in the United States. Methods: Data provided by the World Health Organization were used to evaluate age-specific mortality trends from 1969 through 1986 for lung, breast, prostate, stomach, and colorectal cancers and for all other sites considered as a group. We also assembled and analyzed data from the Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute for the same sites and age groups from 1973 through 1986. Results: Over the period 1969 through 1986, recorded cancer mortality in persons aged 45 years and older in the six regions studied has increased for lung, breast, and prostate cancers in most age groups, while the decline in stomach cancer mortality is substantial. The increase in lung cancer deaths in men aged 45-54 years has slowed greatly or reversed in all areas except Eastern Europe and East Asia. Trends for intestinal cancer vary by age and region. For all other sites considered as a group, increases have occurred for persons older than 64 years in most regions. In Eastern Europe, there are disturbingly high rates and rapid increases for several of the major forms of cancer in persons aged 45-54 years. In general, trends for cancer incidence in the United States parallel those for mortality. For intestinal cancer, however, incidence has increased while mortality has declined. Conclusions: The trends we report cannot be explained solely by changes in cigarette smoking or aging. Other causes of changes in cancer incidence and mortality need to be determined. Implications: The increasing and decreasing trends in mortality from and incidence of cancer that we found are important for health care planning and may also suggest opportunities for research in cancer prevention. [J Natl Cancer Inst 84: 313-320, 1992