Low-Complexity Energy-Efficient Broadcasting in One-Dimensional Wireless Networks

In this paper, we investigate the transmission range assignment for N wireless nodes located on a line (a linear wireless network) for broadcasting data from one specific node to all the nodes in the network with minimum energy. Our goal is to find a solution that has low complexity and yet performs close to optimal. We propose an algorithm for finding the optimal assignment (which results in the minimum energy consumption) with complexity O(N^2). An approximation algorithm with complexity O(N) is also proposed. It is shown that, for networks with uniformly distributed nodes, the linear-time approximate solution obtained by this algorithm on average performs practically identical to the optimal assignment. Both the optimal and the suboptimal algorithms require the full knowledge of the network topology and are thus centralized. We also propose a distributed algorithm of negligible complexity, i.e., with complexity O(1), which only requires the knowledge of the adjacent neighbors at each wireless node. Our simulations demonstrate that the distributed solution on average performs almost as good as the optimal one for networks with uniformly distributed nodes.Comment: 17 page

PREDSTAVLJANJE NOVOGA INDEKSA ODRŽIVOGA RAZVOJA U RUDARSTVU BOKSITA METODOM FUZZY DEMATEL

As an economic activity, mining can have positive and negative effects for the community. These negative impacts along with some of the social, economic, and environmental impacts of mining actions threaten the achievement of sustainable development (SD) goals. Therefore, an impact evaluation of SD indexes is significant for protecting mining actions in line with the objectives of SD. For that reason, a system classification was proposed with the use of the fuzzy decision-making trial and evaluation laboratory (fuzzy DEMATEL) technique to study and analyse eleven impacting factor interrelationships in open pit mines. Since this technique is based upon the opinion of experts, the fuzzy coding technique was used. In this manner, the weight of the impacting factors and their related ratings were chosen to develop a new classification system. Based on the proposed rating system, FDSDI was introduced to describe system-levels qualitatively and quantitatively. The application of FDSDI was investigated in a bauxite mine as a case study. The results show that FDSDI is an easy and effective tool to evaluate sustainability in bauxite mining. Generally, the conducted technique presents a systematic approach for holistic analysis of the impacting factors of SD in open pit mines.Rudarstvo kao ekonomska aktivnost može imati pozitivne i negativne učinke na zajednicu. Ti negativni učinci zajedno s nekim društvenim, ekonomskim i ekološkim utjecajima rudarske djelatnosti prijete ostvarenju ciljeva održivoga razvoja (SD). Stoga je procjena utjecaja na indekse održivoga razvoja važna za zaštitu rudarske djelatnosti u skladu s ciljevima održivoga razvoja. Stoga je predložena sustavna klasifikacija pomoću tehnike neodređenoga ispitivanja i laboratorija za ocjenjivanje (fuzzy dematel) tehnike za proučavanje i analizu jedanaest međusobnih odnosa faktora koji djeluju na otvorenim kopovima. Kako se ova tehnika temelji na mišljenju stručnjaka, primijenjeno je neizrazito kodiranje. Na taj je način izabrana težina utjecajnih čimbenika i povezana ocjena kako bi se razvio nov sustav klasifikacije. Na temelju predloženoga sustava ocjenjivanja uveden je novi indeks održivoga razvoja u rudarstvu boksita metodom fuzzy DEMATEL (FDSDI) za opis kvalitativne i kvantitativne razine na razini sustava. Primjena FDSDI-ja ispitivana je u rudniku boksita kao studija slučaja. Rezultati pokazuju da je FDSDI jednostavan i učinkovit alat za procjenu održivosti u iskopavanju boksita. Općenito, provedena tehnika predstavlja sustavan pristup za holističku analizu faktora utjecaja održivoga razvoja u rudnicima

Application of Vector Control to Permanent Magnet Synchronous Motors Using Chaos Control

This paper presents the idea of vector control for permanent magnet synchronous motor (PMSM) based on chaos theorem, using chaos controller. PMSM will demonstrate chaotic phenomena when its parameters fall into a certain area. To achieve this aim, the sub-system of controller has been designed by considering block diagram structure of vector control for PMSM and by applying the setting of Lyapunov exponents method. Also, asymptotical stability of closed loop system with given controller is shown, using the direct Lyapunov method. The performance of designed controller in chaotic mode is compared with conventional vector control methods. Also, the normal mode for PMSM is considered and the performance of controller is compared. Simulation results indicate that not only does this controller eliminate the chaos in chaotic mode and have good performance but also is able to control the system in normal mode by using almost the smaller control signal effort

PROCJENA UTJECAJA SADRŽAJA VLAGE U UGLJENOJ PRAŠINI NA PREDVIĐANJE INDEKSA NJEZINE EKSPLOZIVNOSTI

Exploring the mechanism of coal dust explosions is essential for the development of safety techniques to prevent coal dust explosions. An explosion index can be used to estimate explosion severity. In this study, the moisture content parameter, one of the intrinsic characteristics of coal dust, was used to estimate the explosion index. For this purpose, 32 samples of coal with different moisture content were collected from different mines in Iran and were prepared as coal rounds. The coal dust explosion process was carried out in a 2-litre closed chamber. After determining the most important and influential parameters, prediction models of the explosion index were presented using linear regression. For this purpose, 75 percent of data was randomly assigned for training and 25 percent of data was used for testing and validation. The performance of these models was assessed through the root mean square error (RMSE), the proportion of variance accounted for (VAF), the mean absolute percentage error (MAPE) and the mean absolute error (MAE). Then the results of the laboratory method were compared with the results of the regression model. The results show that there is a good correlation between the laboratory results and the predictive model obtained through linear regression analysis.Istraživanje eksplozivnosti ugljene prašine iznimno je važno kod razvoja sigurnosnih tehnika za sprječavanje eksplozije ugljene prašine. Indeks eksplozivnosti koristi se za procjenu težine (snage) eksplozije. Pri tomu je sadržaj vlage jedna od intrinističkih varijabli same prašine izravno rabljena za izračun indeksa. U istraživanju su analizirana 32 uzorka različitoga sadržaja vlage prikupljena u različitim iranskim rudnicima. Eksplozivnost prašine ispitana je u dvolitarskim zatvorenim komorama. Određeni su najvažniji, tj. najrizičniji, parametri kojima se predviđa indeks eksplozivnosti uporabom linearne regresije. Skup od 75 % podataka, slučajno odabranih, uporabljen je za uvježbavanje, a 25 % za provjeru. Kvaliteta modela ispitana je korijenom srednje kvadratne pogrješke, udjelom varijance, srednjom apsolutnom postotnom i srednjom apsolutnom pogrješkom. Uspoređeni su rezultati laboratorijskoga testiranja i oni linearne regresijske analize

Relations between Texture Coefficient and Energy Consumption of Gang Saws in Carbonate Rock Cutting Process

Texture coefficient is one of the most influential parameters in rock engineering specifications in various projects including drilling, cutting, permeability of all-section drilling devices, etc. Meanwhile, investigating and forecasting the energy consumption of saw cutters are one of the most important factors in estimating the cutting costs. The present study aims to investigate the relationship between rock texture characteristics and the amount of energy consumption of the gang saw machine in the process of cutting carbonate rocks. To evaluate the effects of texture on the rocks' engineering specifications, 14 carbonate rock samples were studied. A microscopic thin section was made from each rock specimen. Then, five digital images were taken from each section under a microscope and the values of area, environment, the largest diameter and the smallest diameter of all grains in each image were determined. Using these specifications, the coefficient of texture of all rock samples was calculated and the relationship between the texture coefficient and the rate of energy consumption of the gang saw machine was investigated for the studied samples. The study results indicated that there was a significant relation between the texture coefficient and energy consumption rate in the three groups of carbonate rocks

AN EXPERIMENTAL STUDY OF THE REPEATED BLASTING EFFECT ON SURROUNDING ROCK WEAKNESS INCORPORATING ULTRASONIC WAVE VELOCITY MEASUREMENT

Višestruko miniranje ima snažne i kumulativne učinke stvarajući zonu različitih stupnjeva oštećenja i oslabljenja. Prikazani su rezultati eksperimenta kojim se ispitala kumulativna oslabljenost stijene stvorena višestrukim miniranjem, a kojim su se simulirali takvi postupci kod površinskih kopova. Analiza je načinjena na četirima betonskim blokovima u kojima su ispitane dvije minske mreže. Unutar blokova izmjerena je brzina stvorenih nadzvučnih valova. Izračunan je indeks intenziteta oslabljenosti, koji je razlika brzine vala prije i nakon detonacije. Vrijednost je pokazala kako je indeks izgubio na vrijednosti tijekom drugoga kruga detoniranja. Također, raspodjela oslabljenih zona bila je puno pravilnija u drugome krugu. Razdioba energije eksplozije također je bila različita ovisno o fazi detoniranja. Rezultati su povećali znanje o utjecaju višestrukoga miniranja na okolne stijene, stvaranju oslabljenih zona te promjeni mehaničkih svojstava.Repeated blasting leads to progressive and cumulative effects on blast-induced damage zones in which the extension zone and the intensity of weakness are dynamic. This paper presents the results of an experimental study intended to examine cumulative weakness intensity due to repeated blasting to simulate a bench blasting situation in open pit mining. For this purpose, four concrete blocks were made which were subjected to two different blasting patterns. A grid was designed to measure ultrasonic wave velocity in the blocks. The blocks were blasted by a detonating cord and their weakness intensity index was defined by calculating the difference between wave velocity before and after blasting rounds. The results show that weakness intensity due to the second blasting round was increased when compared to the results of the first blasting round. In addition, dispersion of weakness produced by the second blasting round was more uniform. Moreover, explosive energy distribution in terms of the initiation and propagation of fractures caused by the second blasting round affected the performance of the second blasting round energy. This study increased the current understanding of the repeated blasting cumulative effect on a surrounding rock mass in terms of weakness which affects the mechanical properties of a rock mass

SIMULACIJA DOSTUPNOSTI I ANALIZA RADA OKLOPNOGA TRANSPORTERA U ŠIROKOČELNOME RUDARENJU

Since coal mining production systems are very complex, repairing equipment is expensive. If a system failure occurs, it will cause disturbances such as inoperable equipment, reduced operating time, increased production costs, and reduced equipment performance. Therefore, it is necessary to consider the availability of the coal mining industry more than ever. For this purpose, the Armored Face Conveyor (AFC) machine failure data was gathered over a period of 29 months from the Tabas Coal Mine. Descriptive statistics, trends, and serial correlation tests of the data were calculated. Then, the system’s mean and point availability were simulated. Based on the results, the mean availability (all events) and point availability (all events) at 360000 h are 96% and 95%, respectively. The mean time to first failure (MTTFF) of the AFC machine was about 23.61 h. The ReliaSoft Failure Criticality Index, ReliaSoft Downing Event Criticality Index, and ReliaSoft Downtime Criticality Index electrical equipping have the largest effect, whereas the main drive subsystem is the least important. Analysis showed that availability has a direct correlation to activity management and improvements in the quality, efficiency, and the product extraction.Sustavi proizvodnje ugljena u rudnicima vrlo su složeni, stoga je i popravak opreme skup. Kvar sustava uzrokovat će smetnje kao što je nedostupna oprema, smanjeno vrijeme rada, povećani troškovi proizvodnje i smanjene performanse opreme. Stoga je nužno da se dostupnost industrije ugljena razmatra više nego ikad. U tu svrhu 29 mjeseci prikupljani su podatci o kvaru stroja tipa oklopljenoga širokočelnoga transportera iz rudnika ugljena Tabas. Izračunane su opisna statistika, trendovi i test serijske korelacije podataka. Zatim su simulirane srednje vrijednosti i dostupnost bodova u sustavu. Na temelju rezultata prosječna dostupnost (svi događaji) i dostupnost točke (svi događaji) na 360 000 h iznose 96 % odnosno 95 %. Prosječno je vrijeme do prvoga kvara (MTTFF) transportnog stroja oko 23,61 h. U trima metričkim vrijednostima, ReliaSoft indeksu kritičnosti kvara, ReliaSoft indeksu kritičnosti pada sustava i ReliaSoft indeksu kritičnosti zastoja, električno opremanje ima najveći učinak, dok je glavni pogonski podsustav najmanje važan. Utvrđeno je da analiza dostupnosti kontrolira upravljanje operacijama i poboljšanja u kvaliteti, učinkovitosti i izvedbi linije

Multi-agent based protection scheme using current-only directional overcurrent relays for looped/meshed distribution systems

The complexity of the design of the protection system using directional over current relays, for modern power distribution systems has been increased due to the looped/meshed operation and the penetration of distributed generations. Finding a reliable and efficient protection scheme that can be easily implemented in these distribution systems is a major challenge. An efficient solution could be the use of artificial intelligent-based multi-agent systems. This paper proposes a novel distributed intelligent based multi-agent protection scheme, which makes use of current-only directional over current relays as agents for detecting and locating faults and isolating faulty areas (lines/busbars) in the distribution systems. All agents can make on-board decisions by exchanging binary data, and do not need a control centre, so the safety of the protection system against one-point failures and cyber-attacks is increased. The proposed scheme does not need to exchange analogue data, and, therefore, it prevents the high bandwidth communication links. Moreover, it is free from the traditional coordination between relays. This scheme is implemented on the IEEE-14 bus and IEEE-30 bus test systems with the distributed generations and several scenarios have been simulated to evaluate its performance