Cooling Strategies for Greenhouses in Summer: Control of Fogging by Pulse Width Modulation

The possibilities for improving the control of greenhouse fogging systems, were studied by comparing several combinations of ventilation cooling techniques, shade screening and low-pressure fogging. The study was divided into three parts: experiments, modelling and simulations. In the first part of the paper, ten combinations of five cooling techniques were tested during the summers of 2002 and 2003 in a 132m2 greenhouse with a steel structure and a single-layer methacrylate cover located in Madrid, Spain. An analysis of variance of the climatic parameters was carried out to determine which combinations produced significant differences in inside temperature or relative humidity. Comparing the values for the inside to outside temperature difference, the combination of a shade screen and above-screen fogging achieved a difference in temperature almost the same as that for under-screen fogging, but the relative humidity was significantly lower. In the second part of the study a dynamic model was developed (2002) and validated (2003). The mean absolute error obtained for inside temperature was similar in the fit and the validation and it was less than 1.5 1C in both cases. The model was used to simulate the inside air temperature for a fog system working without shading, and above and under a shade screen. Control algorithms were developed for reducing system water consumption. In the three cases a simple on/off control with a fixed fogging cycle was compared with a pulse width modulation (PWM) strategy, in which the duration of the fogging pulse was increased as a function of inside temperature. The strategies with PWM applied to the fog system were able to reduce water consumption by 8–15% with respect to the strategies with a fixed fogging cycle

Giraffes, Institutions and Neglected Firms

Certain securities - in particular, those of small capitalization firms - are generally unsuited to the investment requirements of financial institutions, hence attract minimal coverage by analysts. As a result, these securities may offer a premium as a compensation for associated information deficiencies and/or because pricing inefficiencies exist as a result of the lack of information. An analysis of 510 firms over a 10-year period indicates that the shares of those firms neglected by institutions outperform significantly the shares of firms widely held by institutions. The superior performance persists over and above any small firm effect ; that is, both small and medium-sized neglected firms exhibit superior performance. The neglected firm effect suggests some potentially rewarding investment strategies for individuals and institutions alike

Chaotic to ordered state transition of cathode-sheath instabilities in DC glow discharge plasmas

Transition from chaotic to ordered state has been observed during the initial stage of a discharge in a cylindrical dc glow discharge plasma. Initially it shows a chaotic behavior but increasing the discharge voltage changes the characteristics of the discharge glow and shows a period substraction of order 7 period $\to$ 5 period $\to$3 period $\to$1 period i.e. the system goes to single mode through odd cycle subtraction. On further increasing the discharge voltage, the system goes through period doubling, like 1 period $\to$ 2 period $\to$ 4 period. On further increasing the voltage, the system goes to stable state without having any oscillations.Comment: chathode-sheath, instabilities, chaos, period-subtraction, bifurcation, dc-discharg

Multimedia delivery in the future internet

The term “Networked Media” implies that all kinds of media including text, image, 3D graphics, audio and video are produced, distributed, shared, managed and consumed on-line through various networks, like the Internet, Fiber, WiFi, WiMAX, GPRS, 3G and so on, in a convergent manner [1]. This white paper is the contribution of the Media Delivery Platform (MDP) cluster and aims to cover the Networked challenges of the Networked Media in the transition to the Future of the Internet. Internet has evolved and changed the way we work and live. End users of the Internet have been confronted with a bewildering range of media, services and applications and of technological innovations concerning media formats, wireless networks, terminal types and capabilities. And there is little evidence that the pace of this innovation is slowing. Today, over one billion of users access the Internet on regular basis, more than 100 million users have downloaded at least one (multi)media file and over 47 millions of them do so regularly, searching in more than 160 Exabytes1 of content. In the near future these numbers are expected to exponentially rise. It is expected that the Internet content will be increased by at least a factor of 6, rising to more than 990 Exabytes before 2012, fuelled mainly by the users themselves. Moreover, it is envisaged that in a near- to mid-term future, the Internet will provide the means to share and distribute (new) multimedia content and services with superior quality and striking flexibility, in a trusted and personalized way, improving citizens’ quality of life, working conditions, edutainment and safety. In this evolving environment, new transport protocols, new multimedia encoding schemes, cross-layer inthe network adaptation, machine-to-machine communication (including RFIDs), rich 3D content as well as community networks and the use of peer-to-peer (P2P) overlays are expected to generate new models of interaction and cooperation, and be able to support enhanced perceived quality-of-experience (PQoE) and innovative applications “on the move”, like virtual collaboration environments, personalised services/ media, virtual sport groups, on-line gaming, edutainment. In this context, the interaction with content combined with interactive/multimedia search capabilities across distributed repositories, opportunistic P2P networks and the dynamic adaptation to the characteristics of diverse mobile terminals are expected to contribute towards such a vision. Based on work that has taken place in a number of EC co-funded projects, in Framework Program 6 (FP6) and Framework Program 7 (FP7), a group of experts and technology visionaries have voluntarily contributed in this white paper aiming to describe the status, the state-of-the art, the challenges and the way ahead in the area of Content Aware media delivery platforms

Probing Individual Environmental Bacteria for Viruses by Using Microfluidic Digital PCR

Viruses may very well be the most abundant biological entities on the planet. Yet neither metagenomic studies nor classical phage isolation techniques have shed much light on the identity of the hosts of most viruses. We used a microfluidic digital polymerase chain reaction (PCR) approach to physically link single bacterial cells harvested from a natural environment with a viral marker gene. When we implemented this technique on the microbial community residing in the termite hindgut, we found genus-wide infection patterns displaying remarkable intragenus selectivity. Viral marker allelic diversity revealed restricted mixing of alleles between hosts, indicating limited lateral gene transfer of these alleles despite host proximity. Our approach does not require culturing hosts or viruses and provides a method for examining virus-bacterium interactions in many environments

Stationary solutions of the one-dimensional nonlinear Schroedinger equation: II. Case of attractive nonlinearity

All stationary solutions to the one-dimensional nonlinear Schroedinger equation under box or periodic boundary conditions are presented in analytic form for the case of attractive nonlinearity. A companion paper has treated the repulsive case. Our solutions take the form of bounded, quantized, stationary trains of bright solitons. Among them are two uniquely nonlinear classes of nodeless solutions, whose properties and physical meaning are discussed in detail. The full set of symmetry-breaking stationary states are described by the $C_{n}$ character tables from the theory of point groups. We make experimental predictions for the Bose-Einstein condensate and show that, though these are the analog of some of the simplest problems in linear quantum mechanics, nonlinearity introduces new and surprising phenomena.Comment: 11 pages, 9 figures -- revised versio

Exact closed form analytical solutions for vibrating cavities

For one-dimensional vibrating cavity systems appearing in the standard illustration of the dynamical Casimir effect, we propose an approach to the construction of exact closed-form solutions. As new results, we obtain solutions that are given for arbitrary frequencies, amplitudes and time regions. In a broad range of parameters, a vibrating cavity model exhibits the general property of exponential instability. Marginal behavior of the system manifests in a power-like growth of radiated energy.Comment: 17 pages, 7 figure

Payday

Legislation lags behind technology all too often. While trillions of dollars are exchanged in online transactions—safely, cheaply, and instantaneously—workers still must wait two weeks to a month to receive payments from their employers. In the modern economy, workers are effectively lending money to their employers, as they wait for earned wages to be paid. The same worker who taps a credit card to pay for groceries in semiautomated checkout lines depends on dated payroll systems that only transfer payments on a “payday.” Workers, especially those living paycheck-to-paycheck, are hard-pressed to meet their daily needs and turn to expensive, short-term credit products—notably, payday lenders. While the need for credit is a real one, credit providers charge a steep price, often culminating in endless debt spirals. So, why does the payday still exist? This Article studies various explanations—economic, historical, behavioral, and legal. A primary conclusion is that the payday owes its existence to legacy legal architecture. That is, payday is a software problem, not a hardware problem. The hardware—i.e., money and payroll technology—is here. We can pay workers daily; in fact, gig economy workers in developing countries will often be paid more quickly than an American employee for the same work. What holds us back is our legal software: dated Eisenhower-era legislation that failed to anticipate technological change. Surprisingly, even pro-worker legislation, such as minimum wage laws, inadvertently encourages the practice. By revealing the overlooked and dated legal infrastructure that sustains the payday, this Article suggests a path for legal reform. Daily streams of payment to workers are feasible, practical, and far more efficient than most people realize. A focused reform could effectively bring an end to the puzzling and pernicious practice of having workers lend money to their employers while they wait for their payday

Reputation Failure: The Limits of Market Discipline in Consumer Markets

Many believe that consumersourced reputational information about products would increasingly replace topdown regulation Instead of protecting consumers through coercive laws reputational information gleaned from the wisdom of the crowd would guide consumer decision making There is now a growing pressure to deregulate in diverse fields such as contracts products liability consumer protection and occupational licensingbrbrThis Article presents a common failure mode of systems of reputation Reputation Failure By spotlighting the publicgood nature of reviews rankings and even gossip this Article shows the mismatch between the private incentives consumers have to create reputational information and its social value As a result of this divergence reputational information is beset by participation selection and social desirability biases that systematically distort it The Article argues that these distortions are inherent to most systems of reputation and that they make reputation far less reliable than traditionally understoodbrbrThe limits of reputation highlight the centrality of the law to the future of the marketplace Proper legal institutions can deal not only with the symptoms of reputation failure ” consumer mistakes ” but improve the flow and quality of reputational information thus correcting reputation failures before they arise The Article offers a general framework and explores a number of strategies A more robust system of reputation can preserve consumer autonomy without sacrificing consumer welfar