Hydrogen-methane fuel control systems for turbojet engines

Design, development, and test of a fuel conditioning and control system utilizing liquid methane (natural gas) and liquid hydrogen fuels for operation of a J85 jet engine were performed. The experimental program evaluated the stability and response of an engine fuel control employing liquid pumping of cryogenic fuels, gasification of the fuels at supercritical pressure, and gaseous metering and control. Acceptably stable and responsive control of the engine was demonstrated throughout the sea level power range for liquid gas fuel and up to 88 percent engine speed using liquid hydrogen fuel

Evaluation of techniques for removal of spacecraft contaminants from activated carbon

Alternative techniques for the regeneration of carbon contaminated with various spacecraft contaminants were evaluated. Four different modes of regeneration were evaluated: (1) thermal desorption via vacuum, (2) thermal desorption via nitrogen purge, (3) in-situ catalytic oxidation of adsorbed contaminants, and (4) in-situ non-catalytic oxidation of adsorbed contaminants

Some Field Instruments and Their Applications

Physiology and ecology depend for their constructive development largely upon the applications of physico-chemical concepts to living organisms and their environment, to their life processes, reactions, and interrelations. A concept is valuable biologically in so far as it can be applied and used as a tool for better understanding of the phenomena related to life. Ecology, as the study of the relations between organisms and their environment and of the interrelations of organisms, depends primarily upon the findings of physiology (Clements, 1905). But to apply physicochemical concepts and hence make them of value to the physiologist or ecologist commonly requires practicable instrumental methods, and the lack of these often causes a valuable concept to remain sterile, so far as the physiologist or ecologist is concerned, for years after it might have been profitably applied. It is but recently that physiologists and ecologists have made full use of electrolytic dissociation of acids in their field of work although the essential facts were clearly set forth by Arrhenius in 1887 and 8, the recent activity of biologists in this field having followed the development not of the concept but of suitable colorimetric and electrometric methods. Physiology and ecology, as well as the applied branches of biology such as agriculture and forestry, seem fated to lag far behind their physico-chemical opportunities. Experimental physiology and ecology, as distinguished from descriptive, are at present in great need of improved methods and instruments. Recent developments in physical, colloidal, and organic chemistry have left the biologist. far behind. Even a branch of phyto-chemistry so well developed as the chemistry of pigments has still to receive its full physiological and ecological application. A method, an instrument or other tool capable of use by the biologist is always a prerequisite to the application of a concept; physiological-ecological investigation still depends upon the development of simple practicable methods and instruments. But with the growing detail of biology, chemistry, and physics the accuracy and often the complexity of methods and instruments must be increased. The time has passed when an investigator needs only the training and skill of a tinker. Many of our methods are crude in the extreme and further progress must await refinements both of methods and instruments. The man who successfully essays physiological-ecological experimentation must have a reserve of physico-chemical training and skill as well as a biological background; a glance through any of our periodicals will, however, reveal how little this is appreciated. Field experimentation in biology is the most backward phase of the subject. It may be easy and even recreational to make collections, descriptions, and observations in the field; it takes one out of doors and into interesting places and there is seldom need to go during inclement weather, but field experimentation is quite a different matter; circumstances are hard, apparatus is ill-suited to field work, and conditions are so variable and can be controlled so imperfectly that conclusions must be carefully tested from every possible angle. The increasing accuracy, delicacy, and complexity of modern biological work impose more and more difficult conditions upon the field experimenter who must have apparatus not only accurate enough to meet the requirements of the case but strong enough to withstand the severe use to which field conditions subject it and simple enough to be usable in the field where many facilities common to laboratories are unobtainable. Field experimentation in physiology and ecology is retarded because of the lack of suitable instruments which are accurate, simple, and sturdy. The very difficulties of the field have, however, produced attractive opportunities, for not only are there truths to be found which have entirely escaped the laboratory worker but many experimentally. established facts still await the fuller confirmation and understanding that only field work can give. The instruments described below are accurate if properly employed, simple, compact, strong, and inexpensive; the methods of use require only supplies which may readily be carried into the field. It is hoped that by their use field workers may be provided with a new means of progress

Some potential blood flow experiments for space

Blood is a colloidal suspension of cells, predominantly erythrocytes, (red cells) in an aqueous solution called plasma. Because the red cells are more dense than the plasma, and because they tend to aggregate, erythrocyte sedimentation can be significant when the shear stresses in flowing blood are small. This behavior, coupled with equipment restrictions, has prevented certain definitive fluid mechanical studies from being performed with blood in ground-based experiments. Among such experiments, which could be satisfactorily performed in a microgravity environment, are the following: (1) studies of blood flow in small tubes, to obtain pressure-flow rate relationships, to determine if increased red cell aggregation can be an aid to blood circulation, and to determine vessel entrance lengths, and (2) studies of blood flow through vessel junctions (bifurcations), to obtain information on cell distribution in downstream vessels of (arterial) bifurcations, and to test flow models of stratified convergent blood flows downstream from (venous) bifurcations

Constructive Multiuser Interference in Symbol Level Precoding for the MISO Downlink Channel

This paper investigates the problem of interference among the simultaneous multiuser transmissions in the downlink of multiple antennas systems. Using symbol level precoding, a new approach towards the multiuser interference is discussed along this paper. The concept of exploiting the interference between the spatial multiuser transmissions by jointly utilizing the data information (DI) and channel state information (CSI), in order to design symbol-level precoders, is proposed. In this direction, the interference among the data streams is transformed under certain conditions to useful signal that can improve the signal to interference noise ratio (SINR) of the downlink transmissions. We propose a maximum ratio transmission (MRT) based algorithm that jointly exploits DI and CSI to glean the benefits from constructive multiuser interference. Subsequently, a relation between the constructive interference downlink transmission and physical layer multicasting is established. In this context, novel constructive interference precoding techniques that tackle the transmit power minimization (min power) with individual SINR constraints at each user's receivers is proposed. Furthermore, fairness through maximizing the weighted minimum SINR (max min SINR) of the users is addressed by finding the link between the min power and max min SINR problems. Moreover, heuristic precoding techniques are proposed to tackle the weighted sum rate problem. Finally, extensive numerical results show that the proposed schemes outperform other state of the art techniques.Comment: Submitted to IEEE Transactions on Signal Processin

What is the impact of psychiatric decision units on mental health crisis care pathways? Protocol for an interrupted time series analysis with a synthetic control study

Background The UK mental health system is stretched to breaking point. Individuals presenting with mental health problems wait longer at the ED than those presenting with physical concerns and finding a bed when needed is difficult – 91% of psychiatric wards are operating at above the recommended occupancy rate. To address the pressure, a new type of facility – psychiatric decision units (also known as mental health decision units) – have been introduced in some areas. These are short-stay facilities, available upon referral, targeted to help individuals who may be able to avoid an inpatient admission or lengthy ED visit. To advance knowledge about the effectiveness of this service for this purpose, we will examine the effect of the service on the mental health crisis care pathway over a 4-year time period; the 2 years proceeding and following the introduction of the service. We use aggregate service level data of key indicators of the performance of this pathway. Methods Data from four mental health Trusts in England will be analysed using an interrupted time series (ITS) design with the primary outcomes of the rate of (i) ED psychiatric presentations and (ii) voluntary admissions to mental health wards. This will be supplemented with a synthetic control study with the same primary outcomes, in which a comparable control group is generated for each outcome using a donor pool of suitable National Health Service Trusts in England. The methods are well suited to an evaluation of an intervention at a service delivery level targeting population-level health outcome and the randomisation or ‘trialability’ of the intervention is limited. The synthetic control study controls for national trends over time, increasing our confidence in the results. The study has been designed and will be carried out with the involvement of service users and carers. Discussion This will be the first formal evaluation of psychiatric decision units in England. The analysis will provide estimates of the effect of the decision units on a number of important service use indicators, providing much-needed information for those designing service pathways

Symbol Based Precoding in The Downlink of Cognitive MISO Channels

This paper proposes symbol level precoding in the downlink of a MISO cognitive system. The new scheme tries to jointly utilize the data and channel information to design a precoding that minimizes the transmit power at a cognitive base station (CBS); without violating the interference temperature constraint imposed by the primary system. In this framework, the data information is handled at symbol level which enables the characterization the intra-user interference among the cognitive users as an additional source of useful energy that should be exploited. A relation between the constructive multiuser transmissions and physical-layer multicast system is established. Extensive simulations are performed to validate the proposed technique and compare it with conventional techniques.Comment: CROWNCOM 201

Criminal Redistribution of Stolen Property: The Need for Law Reform

The development of sophisticated fencing systems for the sale of stolen property to consumers has paralleled the industrialization of society. Although crimes against property and attempts to control them have ancient origins, most theft before the Industrial Revolution was committed for immediate consumption by the thieves and their accomplices rather than for redistribution in the market-place. Society\u27s small population, inadequate transportation and communication systems, and technological inability to mass produce identical goods constrained large-scale fencing because there were few buyers and because stolen property could be readily identified. The unprecedented economic and demographic growth in eighteenth-century Europe, however, removed these practical constraints and made possible the profitable fencing operations that are now firmly institutionalized in industrial societies. Although these social and technological developments are important, they do not provide a complete explanation for the rising theft rate or for the tremendous amount of property successfully redistributed annually. Instead, these problems must be attributed in large part to our society\u27s failure to identify properly the economic relationship underlying theft and redistribution and, consequently, to our inability to develop successful methods of legal control. This review of the history and development of theft and fencing has documented the need for reform in the substantive law and in law enforcement practices. The current state of the law is simply not equipped to cope with a problem that is already extremely serious, and that can only get worse

Criminal Redistribution of Stolen Property: The Need for Law Reform

The development of sophisticated fencing systems for the sale of stolen property to consumers has paralleled the industrialization of society. Although crimes against property and attempts to control them have ancient origins, most theft before the Industrial Revolution was committed for immediate consumption by the thieves and their accomplices rather than for redistribution in the market-place. Society\u27s small population, inadequate transportation and communication systems, and technological inability to mass produce identical goods constrained large-scale fencing because there were few buyers and because stolen property could be readily identified. The unprecedented economic and demographic growth in eighteenth-century Europe, however, removed these practical constraints and made possible the profitable fencing operations that are now firmly institutionalized in industrial societies. Although these social and technological developments are important, they do not provide a complete explanation for the rising theft rate or for the tremendous amount of property successfully redistributed annually. Instead, these problems must be attributed in large part to our society\u27s failure to identify properly the economic relationship underlying theft and redistribution and, consequently, to our inability to develop successful methods of legal control. This review of the history and development of theft and fencing has documented the need for reform in the substantive law and in law enforcement practices. The current state of the law is simply not equipped to cope with a problem that is already extremely serious, and that can only get worse