Waste heat utilization in industrial processes

A survey is given of new developments in heat exchangers and heat pumps. With respect to practical applications, internal criteria for plant operation are discussed. Possibilities of government support are pointed out. Waste heat steam generators and waste heat aggregates for hot water generation or in some cases for steam superheating are used. The possibilities of utilization can be classified according to the economic improvements and according to their process applications, for example, gascooling. Examples are presented for a large variety of applications

Unifying autocatalytic and zeroth order branching models for growing actin networks

The directed polymerization of actin networks is an essential element of many biological processes, including cell migration. Different theoretical models considering the interplay between the underlying processes of polymerization, capping and branching have resulted in conflicting predictions. One of the main reasons for this discrepancy is the assumption of a branching reaction that is either first order (autocatalytic) or zeroth order in the number of existing filaments. Here we introduce a unifying framework from which the two established scenarios emerge as limiting cases for low and high filament number. A smooth transition between the two cases is found at intermediate conditions. We also derive a threshold for the capping rate, above which autocatalytic growth is predicted at sufficiently low filament number. Below the threshold, zeroth order characteristics are predicted to dominate the dynamics of the network for all accessible filament numbers. Together, this allows cells to grow stable actin networks over a large range of different conditions.Comment: revtex, 5 pages, 4 figure

Risk Factors For Adult Victimization Among Florida\u27s Homeless Women

Much of the existing research on violence against homeless women has concluded that homeless women are particularly vulnerable to violence and experience victimization at rates often exceeding the rates of housed women. Little research, however, has focused upon the specific risk factors that expose homeless women to physical assault, rape, and stalking. Utilizing a sample of 737 homeless women from the Florida cities of Orlando, Jacksonville, Tampa, and Miami, this study investigated the risk factors for experiencing adult personal victimization. The characteristics of homelessness, demographics, drug and alcohol use, subsistence activities, childhood victimization, mental health status, and criminal activities were examined as predictors of violence. The results indicate that over three-quarters of the sample had experienced violence, physical, sexual, or stalking, as adults. Consistent with prior research, childhood sexual abuse and time spent in jail or prison were significant predictors of violence. However, contrary to prior research, severe childhood physical abuse did not predict adult violence. Rather, the key childhood predictors of adult violence appear to center upon abuse that is primarily emotional in nature. Also contrary to prior research, the excessive use of alcohol or illicit drugs and engaging in risky subsistence activities did not predict violence. The results also imply that the women\u27s experiences of violence may precipitate their episodes of homelessness, indicating that the violence is a cause of their homelessness. Violence against women continues to be a significant social problem particularly among especially vulnerable populations such as homeless women. Such violence deserves the attention of service providers such as healthcare workers, social services, and criminal justice systems

Modeling and quantitative analysis of actin cytoskeleton networks

In eukaryotischen Zellen bildet das Strukturprotein Aktin Polymernetzwerke aus, die sehr dynamisch und für viele zelluläre Prozesse lebenswichtig sind. In dieser Arbeit werden theoretische Konzepte vorgestellt, um die Eigenschaften komplexer Aktin-Netzwerkstrukturen zu verstehen und mit Messungen mittels Fluoreszenz- und Elektronenmikroskopie zu vergleichen. Ein Großteil der Arbeit behandelt dabei flache vernetzte Aktinstrukturen, die durch gerichtete Polymerisation gegen eine äußere Kraft anwachsen. Dieser Netzwerktyp ist ein wichtiger Bestandteil von sich bewegenden Zellen, wird aber auch von intrazellulären Pathogenen zur Fortbewegung missbraucht. Eine zentrale, experimentell messbare Eigenschaft solcher Netzwerke ist ihre Kraft-Geschwindigkeits-Relation. Verschiedene aktuelle Messungen ergaben hierfür widersprüchlich erscheinende Ergebnisse. In einem relativ einfachen physikalischen Modell wird gezeigt, dass in wachsenden Aktin-Netzwerken zwei stationäre Filament-Orientierungsverteilungen miteinander konkurrieren. Strukturelle Übergänge zwischen den beiden Architekturen werden durch Änderung der Wachstumsgeschwindigkeit des Netzwerks initiiert. Mit zusätzlichen Annahmen zur mechanischen Stabilität einzelner Filamente werden die experimentell gefundenen Eigenarten der Kraft-Geschwindigkeits-Relation (eine Abfolge von konvexen und konkaven Verläufen sowie Hysterese) theoretisch begründet. Das Modell wird zusätzlich auf Aktinwachstum gegen gekrümmte Hindernisse wie intrazelluläre Pathogene erweitert. Um in der Zukunft spezifische Vorhersagen des Modells experimentell zu überprüfen, wurde eine Methode zur automatischen Analyse von Elektronenmikroskopiebildern von Aktin-Netzwerken entwickelt. Erste Ergebnisse lassen eine gute Übereinstimmung erwarten. Des Weiteren wurde eine Methode entwickelt, um Änderungen in der Aktin-Struktur von adhärenten Zellen in einem Hochdurchsatzverfahren mit Fluoreszenzmikroskopie zu bewerten

On distance-regularity in graphs

AbstractIf A is the adjacency matrix of a graph G, then Ai is the adjacency matrix of the graph on the same vertex set in which a pair of vertices is adjacent if and only if their distance apart is i in G. If G is distance-regular, then Ai is a polynomial of degree i in A. It is shown that the converse is also true. If Ai is a polynomial in A, not necessarily of degree i, G is said to be distance-polynomial. It is shown that this is a larger class of graphs and some of its properties are investigated

On almost distance-regular graphs

Distance-regular graphs are a key concept in Algebraic Combinatorics and have given rise to several generalizations, such as association schemes. Motivated by spectral and other algebraic characterizations of distance-regular graphs, we study `almost distance-regular graphs'. We use this name informally for graphs that share some regularity properties that are related to distance in the graph. For example, a known characterization of a distance-regular graph is the invariance of the number of walks of given length between vertices at a given distance, while a graph is called walk-regular if the number of closed walks of given length rooted at any given vertex is a constant. One of the concepts studied here is a generalization of both distance-regularity and walk-regularity called $m$-walk-regularity. Another studied concept is that of $m$-partial distance-regularity or, informally, distance-regularity up to distance $m$. Using eigenvalues of graphs and the predistance polynomials, we discuss and relate these and other concepts of almost distance-regularity, such as their common generalization of $(\ell,m)$-walk-regularity. We introduce the concepts of punctual distance-regularity and punctual walk-regularity as a fundament upon which almost distance-regular graphs are built. We provide examples that are mostly taken from the Foster census, a collection of symmetric cubic graphs. Two problems are posed that are related to the question of when almost distance-regular becomes whole distance-regular. We also give several characterizations of punctually distance-regular graphs that are generalizations of the spectral excess theorem

Requirements for an IoT-lock enabling asynchronous physical handovers of temi-trailers in road freight relay-transport

In long-distance road freight transport, capacity utilization of semi-trailers is less than 30 % due to mandatory steering and rest periods. Truck parking spaces are overcrowded while resulting parking search traffic leads to additional emissions. At the same time, the acute driver shortage and customers' expectations of ever faster functioning supply chains force the highest efficiency in transport means and personnel. Multi-carrier relay-transport represents an approach to solving these problems and exploiting untapped efficiency potentials: Via a digital platform, long distances are intelligently divided into short route sections which are distributed among different carriers. At predefined switching points, the asynchronous handover of semi-trailers to rested drivers takes place. To enable a secure cross-company physical handover, IoT-locking mechanisms play a crucial role. This paper details the asynchronous handover process and introduces the technical design of an IoT-lock which provides effective theft protection while the trailer is parked and reliably connects tractor and semi-trailer during transport. Based on an analysis of stakeholder requirements, software functionalities and mechanical properties of the IoT-lock are derived, which ensure effective theft protection as well as real-time data transmission for relay transports. In addition, legal requirements for asynchronous transfers are investigated to determine liability in case of damage or loss. These form the basis for digital handover protocols that record the condition of the freight and trailer during the handover process