Preparation of N-doped graphite oxide for supercapacitors by NH3 cold plasma

In this work, N-doped graphite oxide (GO-P) was prepared by cold plasma treatment of GO using a mixture of NH3 and Ar as the working gas. When the ratios of NH3:Ar were 1:2, 1:3, and 1:4, the specific capacitances of the GO-P(NH3:Ar1:2), GO-P(NH3:Ar1:3), and GO-P(NH3:Ar1:4) were 124.5, 187.7, and 134.6 Fg−1, respectively, which were 4.7, 7.1, and 5.1 times that of GO at the current density of 1 Ag−1. The capacitance retention of the GO-P(NH3:Ar1:3) was 80% when it was cycled 1000 times. The characterization results showed that the NH3 cold plasma could effectively produce N-doped GO and generate more active defects. The N/C ratio and the contents of pyridinic nitrogen and graphitic nitrogen of the GO-P(NH3:Ar1:3) were the highest. These were conducive to providing pseudocapacitance and reducing the internal resistance of the electrode. In addition, the ID/IG of the GO-P(NH3:Ar=1:3) (1.088) was also the highest, indicating the highest number of defects. The results of discharge parameters measurement and in situ optical emission spectroscopy diagnosis of NH3 plasma showed that the discharge is the strongest when the ratio of NH3:Ar was 1:3, thereby the generated nitrogen active species can effectively promote N-doping. The N-doping and abundant defects were the keys to the excellent electrochemical performance of the GO-P(NH3:Ar1:3). NH3 cold plasma is a simple and rapid method to prepare N-doped GO and regulate the N-doping to prepare high-performance supercapacitors.

Overview of photonic devices based on functional materials-integrated photonic crystal fibers

Photonic crystal fibers (PCFs) have brought tremendous advancements due to their predominant features of peculiar air-holes arrangement in two-dimentional direction. Functional materials like metals, magnetic fluids, nematic liquid crystals, graphene and so on, are extensively adopted to integrate with PCFs to get extraordinary transmission properties. This review takes the development stages of photonic devices based on functional materials-infiltrated PCFs into consideration, covering the overview of common materials and their photoelectric characteristics, the state-of-art infiltrating/coating techniques, as well as the corresponding applications involving polarization filtering and splittering devices in optical communication and sensing elements related to multiple parameters measurement. The cladding air hole of PCFs provides a natural optofluidic channel for materials being introduced, light-matter interaction being enhanced, and transmission properties being extended, where a lab on a fiber are able to be proceeded. It paves a space for the development of photonic devices in the aspects of compact, multi-functional integration, and electromagnetic resistance as well. According to surface plasmon resonance, the property of tunable refractive indices, and the flexible geometry structures, it comes up to some representative researches on polarization filters, multiplexer-demultiplexers, splitters, couplers and sensors, making a candidate for widespread fields of telecommunication, signal-capacity, and high-performance sensing.

Is it possible to turn a diesel engine into a less pollutant device?

The current tendency in the eastern part of Europe is to modify old diesel engines with the purpose of improving characteristics in terms of horsepower and torque, but also to reduce the generated pollution. The diesel engines are still in use, against to the tendencies of renouncing to their support, at least in larger urban & industrial areas, where the pollution level, especially the particulate matter (particles PM10, PM2.5) and ozone concentrations, also the NOx are supposed to be generated mostly by diesel engine vehicles. The paper presents results concerning the influence of modifying the diesel engine control unit’s parameters, such as injection quantity, start of injection, intake air pressure and all the others correlated for better performance. The article brings into attention possibilities to reduce the exhaust pollution concentrations, correlated by simultaneous ways of improving the external characteristics of the engine by modifying the engine control unit’s parameters. Measurement results of a compression ignited internal combustion engine before and after the retrofitting, by reparametrization, meaning changing the parameters are presented and discussed.

ANALYSIS OF THE capabilities OF the CLOSED-OPEN SYSTEM CORRECTION scheme FOR MEASURING VIBRATIONS OF AIRCRAFT STRUCTURal ELEMENTS

В настоящее время в связи со всевозрастающей степенью сложности проектирования, производства и эксплуатации летательных аппаратов все более важным направлением в области развития информационно-измерительных систем становится совершенствование существующих и разработка новых способов измерения параметров вибрации элементов механических конструкций летательных аппаратов. Целью данной работы является анализ возможности и перспективности построения системы для измерения вибраций элементов конструкции самолета на основе использования микромеханических инерциальных измерительных блоков в качестве основных виброметрических измерителей. При этом объектом исследования является система измерения параметров вибрации, а предметом – ее структура, состав, алгоритмы функционирования и ожидаемые точностные характеристики. Для достижения поставленной цели строится информационно-измерительная система на базе инерциальных приборов, а также датчиков для непосредственных измерений перемещений, используются численные и аналитические методы высшей математики и теоретической механики, методы теории случайных процессов и оптимального оценивания. В статье рассмотрены принципы построения такой системы на примере варианта системы измерения параметров вибраций крыла самолета, представлен краткий обзор существующих решений в предметной области и обоснована актуальность и целесообразность предложенного варианта технического решения. Приведены базовый состав и структура системы, описаны основные принципы ее работы, основанные на использовании данных датчиков перемещения, инерциальных измерителей и оптимального калмановского оценивания и коррекции. Показаны основные алгоритмы работы системы, включая алгоритмы ориентации и навигации, оценивания и коррекции при замкнуто-разомкнутой схеме включения оптимального фильтра Калмана, алгоритм вычисления параметров вибрации, представленыматематические модели ошибок основных измерителей системы, показаны полученные предварительные результаты имитационного моделирования, демонстрирующие работоспособность системы и ее ожидаемые приемлемые точностные характеристики, подтверждающие возможность эффективного использования системы и перспективность выбранного направления работ. At present, because of the ever-increasing degree of complexity of aircrafts design, production and operation, the improvement of the existing methods and development of new ones for vibration parameters measurement of aircrafts mechanical structural elements is still an important direction in the field of information-measurement systems development. The purpose of this work is to analyze the possibility and prospects of constructing a system for measuring vibrations of aircraft structural elements based on the use of micromechanical inertial measurement units as the main vibrometric transducers. In this case, the object of research is the vibration parameters measurement system, and the subject is its structure, composition, operations algorithms and the expected accuracy characteristics. To achieve this purpose, an information-measurement system is built on the basis of inertial devices, as well as sensors for direct displacements measurements, numerical and analytical methods of higher mathematics and theoretical mechanics, methods of random processes theory and optimal estimation are used. The article discusses the principles of constructing such system taking as an example a system for measuring the vibration parameters of an aircraft wing, provides a brief overview of the existing solutions in this field of applications and substantiates the relevance and expediency of the proposed methodology of the technical solution. The basic components and structure of the system are presented, the basic principles of its operation are described, based on the use of data from displacement sensors, inertial meters and optimal Kalman estimation and correction. The main algorithms of the system operation are shown, including the orientation and navigation algorithm, estimation and correction algorithm for a closed-open scheme of optimal Kalman filter inclusion in the system, algorithm for calculating vibration parameters, beside the mathematical errors models of the main system sensors and channels are presented, preliminary results of simulation modeling are shown and they demonstrate the operability of the system and its expected acceptable accuracy characteristics, confirming the possibility of the effective use of the proposed system and the prospects of the chosen direction of work.

A multi-criteria analysis of sewer monitoring methods for locating pipe blockages and manhole overflo

This article is devoted to the aggregation of existing methods for monitoring sewerage systems into a single symbiosis, in particular methods for identifying the locations of clogged pipes and manhole overflows. Clogging of sewers is a frequent problem in large cities, entailing overfilling of manholes with sewage and disruption of the whole sewage system. Today, there are several methods for monitoring sewers: visual, acoustic and laser. Each method is represented by a wide range of devices with different characteristics and applications. The analysis identified the main technical and economic characteristics for each solution presented. Then, on the basis of the data obtained, a multi-criteria analysis was made according to several parameters: measurement accuracy, maximum diameter of the inspected pipe, type of pipe, cost. For the most objective selection, each parameter was given its own weight, and all parameters were normalized for their objective comparison. On this basis, all solutions were sorted by maximum values for each criterion, taking into account the selection by weights. As a result of the multicriteria analysis, five combinations of solutions were built, including several monitoring methods.

Application of Optimal Kalman Filter to Improve the Accuracy of Aircraft Wing Vibration Parameters Measurement System

This paper discusses the advantages of constructing a vibration parameters measurement system of an aircraft wing using mems IMUs. In addition to mems IMUs, the system makes use of displacement sensor and navigation system as secondary measurements, along with the optimal Kalman filter estimation. The basic principles of system operation are described. The main algorithms of the system and its errors mathematical model are presented. The results of simulation are presented, demonstrating the expected measurement accuracy of the system as a whole.