HEAT EXCHANGER NETWORK SYNTHESIS CONSIDERING CHANGING PHASE STREAMS

The Pinch Design Method was developed considering one-phase streams, with constant specific heats (Cp) throughout streams temperature ranges. Its first stage, the determination of utilities targets and pinch point (PP), is ruled by the number of streams, their temperatures and MCp. But, for changing phase streams, the usual description of the Cp behavior by a constant value can lead to errors in this stage and, hence, in the synthesis one. This work proposes a procedure to deal with these streams and discusses its results through an example involving multicomponent streams. First, bubble (BP) and dew (DP) points of the streams are estimated. Then, changing phase streams are split into sub-streams, using BP and DP as bounds. For each one, an effective Cp is estimated as the division of the enthalpy change by the respective temperature difference. Results obtained show significant changes on the PP, utilities targets and network proposed structure

Engineering Benchmarks for Planning: the Domains Used in the Deterministic Part of IPC-4

In a field of research about general reasoning mechanisms, it is essential to have appropriate benchmarks. Ideally, the benchmarks should reflect possible applications of the developed technology. In AI Planning, researchers more and more tend to draw their testing examples from the benchmark collections used in the International Planning Competition (IPC). In the organization of (the deterministic part of) the fourth IPC, IPC-4, the authors therefore invested significant effort to create a useful set of benchmarks. They come from five different (potential) real-world applications of planning: airport ground traffic control, oil derivative transportation in pipeline networks, model-checking safety properties, power supply restoration, and UMTS call setup. Adapting and preparing such an application for use as a benchmark in the IPC involves, at the time, inevitable (often drastic) simplifications, as well as careful choice between, and engineering of, domain encodings. For the first time in the IPC, we used compilations to formulate complex domain features in simple languages such as STRIPS, rather than just dropping the more interesting problem constraints in the simpler language subsets. The article explains and discusses the five application domains and their adaptation to form the PDDL test suites used in IPC-4. We summarize known theoretical results on structural properties of the domains, regarding their computational complexity and provable properties of their topology under the h+ function (an idealized version of the relaxed plan heuristic). We present new (empirical) results illuminating properties such as the quality of the most wide-spread heuristic functions (planning graph, serial planning graph, and relaxed plan), the growth of propositional representations over instance size, and the number of actions available to achieve each fact; we discuss these data in conjunction with the best results achieved by the different kinds of planners participating in IPC-4

Essential Nutrients for Bone Health and a Review of their Availability in the Average North American Diet

Osteoporosis and low bone mineral density affect millions of Americans. The majority of adults in North America have insufficient intake of vitamin D and calcium along with inadequate exercise. Physicians are aware that vitamin D, calcium and exercise are essential for maintenance of bone health. Physicians are less likely to be aware that dietary insufficiencies of magnesium, silicon, Vitamin K, and boron are also widely prevalent, and each of these essential nutrients is an important contributor to bone health. In addition, specific nutritional factors may improve calcium metabolism and bone formation. It is the authors’ opinion that nutritional supplements should attempt to provide ample, but not excessive, amounts of factors that are frequently insufficient in the typical American diet

Single Molecule Analysis Research Tool (SMART): An Integrated Approach for Analyzing Single Molecule Data

Single molecule studies have expanded rapidly over the past decade and have the ability to provide an unprecedented level of understanding of biological systems. A common challenge upon introduction of novel, data-rich approaches is the management, processing, and analysis of the complex data sets that are generated. We provide a standardized approach for analyzing these data in the freely available software package SMART: Single Molecule Analysis Research Tool. SMART provides a format for organizing and easily accessing single molecule data, a general hidden Markov modeling algorithm for fitting an array of possible models specified by the user, a standardized data structure and graphical user interfaces to streamline the analysis and visualization of data. This approach guides experimental design, facilitating acquisition of the maximal information from single molecule experiments. SMART also provides a standardized format to allow dissemination of single molecule data and transparency in the analysis of reported data

Use of the open-ended probe technique for the dielectric characterization of biological tissues at low frequencies

The open-ended probe is a popular technique adopted for the measurement of dielectric properties of biological tissues. Commercial probes are commonly used for measurements at frequencies higher than 500 MHz because under this frequency limit the error of reconstruction increases and reaches not acceptable values. The aim of this paper is to understand how to improve the accuracy of this technique for the dielectric characterization of samples at low frequencies. Theorical studies have shown that the measurement accuracy is related to a capacitive parameter of the probe which is dependent on the radial dimensions of the probe itself. Starting from this assumption, in this work some experimental measurements have been done on known liquids finding that the dimensions of the probe can influence the results. It is demonstrated that the choice of the probe with the optimal structure can improve the accuracy of measurements at low frequencies