Decision trees for uplift modeling with single and multiple treatments

Most classification approaches aim at achieving high prediction accuracy on a given dataset. However, in most practical cases, some action such as mailing an offer or treating a patient is to be taken on the classified objects, and we should model not the class probabilities themselves, but instead, the change in class probabilities caused by the action. The action should then be performed on those objects for which it will be most profitable. This problem is known as uplift modeling, differential response analysis, or true lift modeling, but has received very little attention in machine learning literature. An important modification of the problem involves several possible actions, when for each object, the model must also decide which action should be used in order to maximize profit. In this paper, we present tree-based classifiers designed for uplift modeling in both single and multiple treatment cases. To this end, we design new splitting criteria and pruning methods. The experiments confirm the usefulness of the proposed approaches and show significant improvement over previous uplift modeling techniques.     

Optimization of reinforcement layout of scissor‐type bridge using differential evolution algorithm

Scissors mechanisms are commonly used in safety engineering during the construction of temporary structures, owing to their inherent advantages of foldability, transformability, and reusability. We effectively utilized these scissors mechanism features to develop a lightweight, deployable emergency Mobile Bridge (MB) based on optimization, and control of the folding structure. Here, we discuss the problems of optimal reinforcement layout for the MB by formulating and solving three optimization problems, namely: (a) the load capacity maximization problem, (b) the weight minimization problem, and (c) coupling the load capacity maximization problem and the weight minimization problem. The potential benefits resulting from the application of reinforcement were evaluated using a combination of finite element analysis and an optimization algorithm based on the differential evolution method. The results demonstrate the significant positive influence of the additional reinforcing members. In particular, the limit load was increased by over 10 times, while the weight was decreased to approximately half. The proposed methodology enabled the development of a substantially improved version of the MB characterized by a higher load capacity and lower weight in comparison to the initial bridge design.     

Power system stability enhancement by WAMS-based supplementary control of multi-terminal HVDC networks

This paper deals with supplementary control of a MTDC network designed for the stability enhancement of a AC power system. The proposed control is a WAMS-based control modulating the real and reactive power at the terminals of the DC network. Relevant control formulas have been derived for a linear multi-machine system model with the application of the direct Lyapunov method. Validity and robustness of the proposed control has been verified by computer simulation for a multi-machine test system using a nonlinear model and detailed modeling of power system components. The proposed control is robust and insensitive to changes in the network configuration and loading conditions in the AC power system. In the case, when more of the MTDC networks and/or the HVDC links are used in one interconnected power system the proposed stabilizing control produces additive damping i.e. each controlled network element contributes to the positive damping. Some practical aspects have also been discussed. The proposed WAMS-based stabilizing control of the MTDC network is innovative by both its main concept and the derivation of control formulas using the direct Lyapunov method.     

Towards the improvement of thermal efficiency in lignite‐fired power generation: Concerning the utilization of Polish lignite deposits in state‐of‐the‐art IGCC technology

Integrated coal Gasification Combined Cycle (IGCC) is the most advanced technology for coal‐fired power generation. The two‐stage entrained flow gasification process allows for the use of a wide range of coal, as long as the gasification temperature is above the ash melting point of a used fuel. In this gasification technology, lignite, which often has a low ash melting point, can be preferably utilized. However, ash fluidity is also another importance, because the behaviour of molten slag can diminish a stable ash discharge from a gasifier. As the eligibility of coal ash properties is a considerable factor, water physically and chemically kept in lignite (30 – 60% in mass) attributes to deteriorating gasification efficiency, because it causes significant heat loss and increasing oxygen consumption. Developing a thermal evaporative lignite drying method will be a necessary attempt to apply lignite to the coal gasification process. For those preceded objectives, coal and ash properties and drying characteristics of several grades of Polish lignite, extracted from Belchatow and Turow deposits, have been experimentally investigated in a preliminary study evaluating the applicability and consideration for its utilization in state‐of‐the‐art clean coal technology, IGCC. This paper particularly discusses the eligibility of Polish lignite from the perspective of the fusibility and fluidity of ash melts and the fundamental drying kinetics of lignite in superheated steam in the light of water removal. The viscosity of ash melts is measured at high temperature up to 1700 °C. In the drying tests, the significant influence of structural issues, because of the provenance and origin of lignite on the drying characteristics, was found by applying the method of sensitivity analysis of physical propensity. This paper concludes that the investigated Polish lignite has characteristics favourable for utilization in IGCC technology, once the precautions related to its high moisture have been carefully addressed. Copyright © 2016 John Wiley & Sons, Ltd.     

Polycationic star polymers with hyperbranched cores for gene delivery

Core-shell type stars synthesized via atom transfer radical polymerization were used for the delivery of nucleic acids. The interior of the stars consisted of hyperbranched poly(arylene oxindole), while the arms were composed of poly(N,N-dimethylaminoethyl methacrylate). The length of the star arms varied in degree of polymerization (DP) from 14 to 98. The hydrodynamic radius of the structures measured in water indicated the presence of small aggregates, while isolated stars ranging in size from 14 to 29 nm were seen in organic solvent. The phase transition temperatures of the stars in water, measured in basic conditions, were shifted to lower values with increasing DP of the arms. Stable polyplexes of stars with plasmid DNA were formed. Their size varied from 300 nm to 400 nm, depending upon the DP of arms. The zeta potential of the polyplexes was positive, which facilitated their cellular uptake. The DP of the arms influenced the transfection efficiency of HT-1080 cells, demonstrating that stars are promising candidates for synthetic gene vectors.     

Polyhydroxyalkanoate‐based drug delivery systems

Microbial polyhydroxyalkanoates (PHAs) have been a subject of significant research interest in the past few decades. The recent development of novel functionalized PHAs has opened up new possibilities to combine the good biocompatibility of PHA‐based drug delivery systems to, for example, improve drug loading and release properties, targeting or imaging functionalities. This mini‐review presents some recent scientific developments in the preparation of functionalized PHAs, PHA–drug and PHA–protein conjugates, multifunctional PHA nanoparticles and micelles as well as biosynthetic PHA particles for drug delivery. These developments in combination with the generally excellent biocompatibility of PHA materials are expected to further expand the interest in PHA materials for drug delivery and other therapeutic applications. © 2016 Society of Chemical Industry     

Online version of the theorem of Thue

A sequence S is nonrepetitive if no two adjacent blocks of S are the same. In 1906 Thue proved that there exist arbitrarily long nonrepetitive sequences over 3 symbols. We consider the online variant of this result in which a nonrepetitive sequence is constructed during a play between two players: Bob is choosing a position in a sequence and Alice is inserting a symbol on that position taken from a fixed set A. The goal of Bob is to force Alice to create a repetition, and if he succeeds, then the game stops. The goal of Alice is naturally to avoid that and thereby to construct a nonrepetitive sequence of any given length.We prove that Alice has a strategy to play arbitrarily long provided the size of the set A is at least 12. This is the online version of the theorem of Thue. The proof is based on nonrepetitive colorings of outerplanar graphs. On the other hand, one can prove that even over 4 symbols Alice has no chance to play for too long. The minimum size of the set of symbols needed for the online version of Thue?s theorem remains unknown.     

Experimental and numerical verification of transient spatial temperature distribution in thick-walled pressure components

The aim of this work is to present a method to determine the transient-state spatial temperature distribution in a cylindrical component. The presented method involves solving the inverse heat conduction problem based on the Finite volume method (FVM). This approach enables determination of transient-state temperature fields with boundary conditions known on one surface of the component only. The proposed method is verified using the laboratory installation located at the Cracow University of Technology. The main components of the laboratory stand are, among others, a steam outlet header and a steam boiler. During the experiment, the steam header is heated up abruptly from the inside by contact with dry saturated steam. The spatial transient-state temperature distribution within the steam outlet header is determined using the proposed method, which is based on temperature measurements made by 19 thermocouples located on the outer surface of the component. The temperature histories in three selected nodes are compared with the measurement results obtained from thermocouples located inside the component wall. The exact location of the thermocouples corresponds to the nodal position at selected control volumes. Moreover, the Ansys Mechanical APDL software is used to verify calculations and experimental data. A transient- state simulation is performed. The temperature histories at the inner and outer surfaces are set as the model boundary conditions. In order to enable verification of the temperature measurements, the component discrete model includes nodes at appropriate locations. An error analysis is performed between calculated and measured temperature values. The results obtained from the numerical and experimental validation demonstrate fully satisfactory agreement. Additionally, a stress analysis of the outlet header is performed in the Ansys software based on the transient-state temperature distribution within the steam outlet header. The method proposed in this paper is a convenient and accurate tool for monitoring working conditions of the power boiler thick-walled components.     

Performance indices of a common rail-system CI engine powered by diesel oil and biofuel blends

Conventional fuels used for supplying internal combustion piston engines include petrols and diesel oils produced from petroleum. These are a non-renewable energy source. The environmental policy of the European Union is geared towards increasing the share of renewable fuels in the overall energy consumption. An alternative fuel originating from a renewable source, which could be used for feeding self-ignition internal combustion engines are the fatty acid methyl esters (FAME) of plant oils. The paper reports selected results of testing a 1.3 MULTIJET SDE 90 PS self-ignition engine with the Common Rail reservoir feed system supplied with mixtures of diesel oil and rape oil fatty acid methyl esters (FAME). Tests were carried out on an engine test bed equipped with an eddy-current brake. The purpose of the tests was to determine the economic–energy and ecological indices of engine operation. The concentrations of exhaust gas gaseous components were measured using a MEXA-1600DEGR analyzer, while the particulate concentrations, with a MEXA-1230PM analyzer. In addition, the variations of working medium pressures in the engine chamber and of fuel pressure upstream the injector were recorded as a function of crankshaft rotation angle using the AVL IndiSmart 612 indication system for this purpose. The physicochemical properties of fuels used in the tests were determined using a fuel analyzer. The obtained testing results made it possible to determine and assess the operation indices of the engine fed with mixtures of diesel oil and rape oil fatty acid methyl esters (FAME) with slightly higher ester contents than the requirements of the currently applicable diesel oil standard.     

Impact of Ozonation Process on the Microbiological Contamination and Antioxidant Capacity of Highbush Blueberry (Vaccinum corymbosum L.) Fruit during Cold Storage

In the studies conducted, the impact of the innovative ozonation procedure on the microbial state and antioxidant potential of highbush blueberry (Vaccinum corymbosum L.) stored under cold storage conditions was assessed. Microbiological analysis was carried out to determine the total number of mesophilic aerobic bacteria and the total number of fungi during the storage experiment. In addition, changes in the flavonoid, anthocyanins, and vitamin C content and the total antioxidant capacity were monitored during the storage. The degree of fruit infection with gray mold and anthracnose was determined. It was found that daily ozonation of fruits with a dose of 15 ppm for 30 min, every 12 h, for 28 days effectively reduced the development of aerobic mesophilic bacteria and fungi. On the last day of storage, symptoms of the infection by gray mold were observed in 27.5% of the control fruit, while the absence of symptoms was observed in case of the ozonated fruit. On the other hand, ozone was ineffective in case of inhibiting the infection by anthracnose. Nevertheless, the ozonation process allowed maintaining a high antioxidant potential of the fruit and substantially reduced losses of flavonoids, anthocyanins, and vitamin C. The utilized procedure has proved to be effective, providing the possibility of extensive use of ozone as a factor allowing sustaining a high commercial and consumption value of the fruit over extended time.