Preparation of Crystalline Aluminum Phosphate by the Reaction Using Boron Phosphate

The use of BPO₄ in the synthesis of crystalline AlPO⁴ has been investigated. The best results are obtained if BPO₄ and hydrated alumina are heated in molten KCl: at 1050°C the conversion degree of BPO₄ into AlPO⁴ is >90% (in 4 h). The product consists of the tridymite AlPO⁴ form.     

Prediction of diesel fuel cold properties using artificial neural networks

In this paper, two neural networks, multilayer perceptron and networks with radial-basis function, were used to predict important cold properties of commercial diesel fuels, namely cloud point and cold filter plugging point. The developed models predict the named properties using cetane number, density, viscosity, contents of total aromatics, and distillation temperatures at 10, 50, and 90 vol. % recovery as input data. The training algorithms, number of hidden layer neurons, and number of training data points were optimized in order to obtain a model with optimal predictive ability. The results indicated better prediction of cloud and cold filter plugging points in the case of multilayer perceptron networks. The obtained absolute error mean for the optimal neural network models (0.58°C for the cloud point and 1.46°C for the cold filter plugging point) are within the range of repeatability of standard cold properties determination methods.     

Ultrastructural changes in the cemento‐enamel junction caused by acidic beverages: An in vitro study

The present in vitro study was aimed at evaluating the morphological changes in the cemento‐enamel junction (CEJ) after exposure to acidic beverages using the scanning electron microscopy (SEM). The initial pH and titratable acidity (TA) was analyzed from follow groups: (I) Coca cola, (II) orange juice, (III) Cedevita, (IV) Red Bull, (V) Somersby cider, and (VI) white wine. The CEJ samples (n = 64), obtained from unerupted third molars, were allocated to one control (artificial saliva, n = 16) and six experimental groups (n = 8). The experimental samples were immersed in beverages (50 ml) for 15 min, three times daily, 10 days, and in artificial saliva between immersions. SEM analysis was performed in a blind manner, according to scoring scale. One‐way ANOVA and Tukey's post hoc tests, as well as Kruskal–Wallis and Mann–Whitney U test used for statistical analysis. The pH values of the acidic beverages ranged from 2.65 (Coca cola) to 3.73 (orange juice), and TA ranged from 1.90 ml (Coca cola) to 5.70 ml (orange juice) of NaOH to reach pH 7.0. The SEM analysis indicated statistically significant differences between the control samples and those immersed in acidic beverages. The Groups IV, I, and II, showed the highest CEJ damage grade while those of the Group VI were the lowest. All the tested acidic beverages caused morphological changes in the CEJ with a smaller or larger exposure of dentine surface, and were not always related to the pH or TA of acidic beverages.     

Measurement of the transient electrical and shaft torques in an induction motor drive by the indirect two-speed method

Contents This paper presents a new method, called Indirect Two-Speed Method (ITSM), for obtaining electrical and shaft torques in an induction motor drive by means of measuring the speeds of both lumped-inertia elements assigned to a second order model. The measuring is realized by using high-resolution digital tachometers (represented by incremental encoders), two frequency measurement systems based on the Double-Buffered Method, digitalfiltering of the raw speed data and numerical differentiation of the filtered speed data.

---

Messung transienter Drehmomente eines Induktionsmotor-Antriebs mittels der Indirekten Zwei-Drehzahlen-Methode

Übersicht Im Beitrag wird ein neues Verfahren zur Ermittlung des elektrischen Moments und des Wellen-Drehmoments eines Induktionsmotor-Antriebs vorgestellt. Das als Indirekte Zwei-Drehzahlen-Methode (ITSM) bezeichnete Verfahren geht aus von einem mechanischen Modell zweiter Ordnung und mißt die Drehzahlen beider als konzentrierte Parameter betrachteten Drehmassen. Für die Durchführung werden hochauflösende digitale Tachometer eingesetzt. Die Frequenzmessung erfolgt durch ein Verfahren mit doppelter Pufferung, und es werden die Rohdaten nach digitaler Filterung numerisch differenziert.

     

Neural network Reinforcement Learning for visual control of robot manipulators

It is known that most of the key problems in visual servo control of robots are related to the performance analysis of the system considering measurement and modeling errors. In this paper, the development and performance evaluation of a novel intelligent visual servo controller for a robot manipulator using neural network Reinforcement Learning is presented. By implementing machine learning techniques into the vision based control scheme, the robot is enabled to improve its performance online and to adapt to the changing conditions in the environment. Two different temporal difference algorithms (Q-learning and SARSA) coupled with neural networks are developed and tested through different visual control scenarios. A database of representative learning samples is employed so as to speed up the convergence of the neural network and real-time learning of robot behavior. Moreover, the visual servoing task is divided into two steps in order to ensure the visibility of the features: in the first step centering behavior of the robot is conducted using neural network Reinforcement Learning controller, while the second step involves switching control between the traditional Image Based Visual Servoing and the neural network Reinforcement Learning for enabling approaching behavior of the manipulator. The correction in robot motion is achieved with the definition of the areas of interest for the image features independently in both control steps. Various simulations are developed in order to present the robustness of the developed system regarding calibration error, modeling error, and image noise. In addition, a comparison with the traditional Image Based Visual Servoing is presented. Real world experiments on a robot manipulator with the low cost vision system demonstrate the effectiveness of the proposed approach.     

Liposomes as Carriers of Antimicrobial Drugs

Liposome are promising drug carrier systems being developed. Their successful use in the treatment of several diseases demonstrates that a solid rationale for clinical development of liposomes as antimicrobial drug carriers can be established. There are a number of potential drug candidates for liposome encapsulation. The involvement of several biotechnology companies has culminated in the design and licensing of formulations for the treatment of certain microbial infections and cancers. Understanding of liposome behavior in the body and of the physicochemical mechanisms involved in the interaction of liposome, drug, and cellular targets is essential for their future applications.     

On the determination of characteristic temperatures in power oil transformers during transient states

Contents Under usual assumptions the equations describing thermal phenomena in a transformer are established. Without neglecting any substantially important factor, algorithms are developed for predicting the temperatures in critical spots in non-stationary states occurring either in practice or in load/time diagrams. This paper suggests the determinaton of conductances dependent on temperature and constant capacitances of equivalent thermal circuits of a transformer. They are based on a small number of experiments (as simple as possible) and on a parameter estimation procedure. In such a way the temperatures of transformer parts in different transient states can be determined by computer simulation established on equivalent circuits, so the operators in power and sub-stations will be able to load their transformers close to the permitted limit. It is felt that this paper may give a stimulation for a possible revision of IEC rules.

---

Ermittlung charakteristischer Temperaturen von Leistungs-Öl-Transformatoren im nichtstationären Betrich

Übersicht Die Gleichungen des Temperaturverhaltens eines Transformators werden unter den üblichen Annahmen aufgestellt. Es werden Algorithmen entwickelt, welche die Vorausbestimmung der Temperatur an kritischen Stellen bei nichtstationärem Betrieb erlauben. Vorgeschlagen wird die Bestimmung der temperaturabhängigen und-unabhängigen Parameter auf Grund von wenigen und einfachen Messungen. Damit kann das Personal in Verteilerstationen in die Lage versetzt werden, mit Hilfe von PC's die Belastung der Transformatoren bis zu den zulässigen Grenztemperaturen auszudehnen. Die Autoren möchten damit einen Anstoß zu einer möglichen Überarbeitung von IEC-Vorschriften geben.

     

Economical production of rabies vaccine on cell cultures

By producing the rabies vaccine from cell culture, this vaccination has become safe, with minimal postvaccinal reactions. The first vaccine according to this technology was produced by Pavle (Paul) Fenje, former chief of department of the Pasteur Institute in Novi Sad. Many cell cultures have been introduced so far for the rabies virus multiplication: primary hamster kidney, fetal bovine kidney, chick embryo, continuous cell line monkey kidney (VERO), human diploid cell (HDC), etc. Some possibilities of an economical rabies vaccine production from a continuous BHK-21 cell line have been discussed and recommended.