An analysis of random mechanical failures of bucket wheel excavator

In this article random mechanical failures of bucket wheel excavator at open cast mine "Tamnava Zapad" are analysed. Random mechanical failures of mining equipment may represent an important factor in coal production because these types of failures occur unpredictably. Some of the reasons for the occurrence of such failures are unde-tectable defects, unexplainable causes, and unavoidable failures. In addition, here we have failure of equipment that has a large investment and productivity value. Statistical regularity of the component failure distribution of this system is analysed based on dispatcher's reports about EBS system failures in the period 2003-2011. The proposed distribution is analysed by theoretically, using suitable tests. By using statistical distribution we get the expected uptime of the bucket wheel excavator, for each year, which represents an important factor in maintenance programs and periodic inspections/repairs on bucket wheel excavator and mining components, in general

The Reliability of Bucket Wheel Excavator - Review of Random Mechanical Failures

Statistical regularity of random mechanical failures of the bucket wheel excavator will be considered based on dispatcher’s reports about excavator-conveyors-spreader (ECS-III) on the Tamnava - West Field Open Cast Mine in Lazarevac (Serbia) system failures in the period from 2003 to 2011. This kind of failures happens suddenly due to undetectable defects, unexplainable causes, and unavoidable failures. Reliability functions R(t), failure rate λ(t) and failure density f(t) of the bucket wheel excavator will be empirically determined. It was concluded that the random failures could be well approximated by the Exponential distribution. Below, serial reliability configuration of the BWE subsystem was analysed and the failure frequency as well as the values of the failure rate by subsystems were determined. Finally, proactive maintenance approach, which represents the latest innovation in the field of maintenance, will be presented. This approach to maintenance utilizes various technologies in order to achieve extension of operational life and elimination of reactive maintenance

An analysis of random mechanical failures of bucket wheel excavator

In this article random mechanical failures of bucket wheel excavator at open cast mine "Tamnava Zapad" are analysed. Random mechanical failures of mining equipment may represent an important factor in coal production because these types of failures occur unpredictably. Some of the reasons for the occurrence of such failures are unde-tectable defects, unexplainable causes, and unavoidable failures. In addition, here we have failure of equipment that has a large investment and productivity value. Statistical regularity of the component failure distribution of this system is analysed based on dispatcher's reports about EBS system failures in the period 2003-2011. The proposed distribution is analysed by theoretically, using suitable tests. By using statistical distribution we get the expected uptime of the bucket wheel excavator, for each year, which represents an important factor in maintenance programs and periodic inspections/repairs on bucket wheel excavator and mining components, in general

Carotid Endarterectomy Unexpectedly Resulted in Optimal Blood Pressure Control

Resistant hypertension is defined as hypertension that remains above 140/90 mmHg despite the provision of three or more antihypertensive drugs in a rational combination at full doses and including a diuretic. It is associated with adverse clinical outcome and therefore requires aggressive medical treatment. We present a case of 70-year-old woman who was treated for resistant hypertension with a diuretic, ACE-inhibitor, calcium channel blocker, and with centrally acting antihypertensive, moxonodine. Despite of aggressive medical treatment her blood pressure remained above 160/90 mmHg continuously. Large diagnostic workup excluded common causes of secondary hypertension, but revealed significant carotid stenosis present on left internal carotid artery. Carotid endarterectomy was performed in order to improve cerebrovascular prognosis, but unexpectedly resulted in optimal control of her blood pressure. Two months after operation patient was on only one antihypertensive drug, having blood pressure below 130/85 mmHg. We suggest that in selected patients resistant hypertension could be associated with carotid stenosis and carotid sinus baroreceptor dysfunction. For definite conclusions further studies are warranted

"SIRELA" i bilogorsko-podravsko mljekarstvo (povijesni prikaz razvoja)

Rad prikazuje razvitak mljekarske djelatnosti na bilogorskom i podravskom području, gdje "SIRELA" otkupljuje mlijeko. Opisan je razvitak stočarske proizvodnje, posebice govedarstva, kao i povijest prvih mljekara na ovom području. Na kraju je prikazan razvitak prerade mlijeka u gradu Bjelovaru, središtu ove regije, koji se zaokružuje postojanjem današnje "SIRELE"

Artificial Intelligence and Nature-Inspired Optimization on Integrative Capacity ff Renewable Energy in the Western Balkan

Two artificial intelligence models for the integration of renewable energy sources are developed within this research to contribute to the European Green Plan realization. The review of renewable energy natural potential, on one hand, and installed capacity, on the other hand, in the Western Balkans and twenty-eight European countries is done within this research, as well as emissions. The analyses show that the European countries, sometimes even with lower natural potential in renewables, have installed much more renewable capacities than the Balkans countries with much higher natural potential. According to this, the first artificial intelligence model is developed based on multi-criteria linear regression analysis. This model relies on the correlation between the relevant regressors, i.e. relevant input variables for twenty-eight European countries and the same regressors for a particular Balkans country. Its goal is to find the maximum possible integrative renewable capacity in a Balkans’s country within the real socio-economic environment. The second artificial intelligence model is developed based on multi-criteria evolution genetic algorithms. Its goal is to find the maximum possible integrative renewable capacity within a real electric power system. Nature-inspired optimization is applied. From the framework of a given large number of generations, technical combinations of the degree of renewable energy sources integration, the best populations, i.e. combinations are selected. As nature selects from many generations and allows the best to survive and punishes the „weakˮ, in our case, „weak” combinations are those failing to meet the given conditions and limitations of the real electric power system. A new methodology is offered. Theoretical general formulas are given for both models. Developed models are tested on a numerical experiment of solar energy integration in the Serbia case study. Analyses of sensitivity prove that both models are applicable for all renewable energy sources and countries or regions

Minimally invasive ultrasound guided surgery for extracting stitches as a cause of secondary infections after tendoraphy of the Achilles tendon rupture

Cilj: Prikazati mogućnosti korištenja ultrazvuka u rješavanju kasnih komplikacija nakon kirurškog zbrinjavanja rupturirane Ahilove tetive. Prikaz slučaja: U radu su prikazana dva bolesnika kod kojih se nakon šest i pet godina na mjestu kirurške intervencije zbog rupture Ahilove tetive razvio upalni proces uz formiranje apscesa. Ultrazvučnim pregledom se u oba bolesnika dijagnosticira postojanje apscesa i stranog tijela u smislu zaostalog konca. Pod kontrolom ultrazvuka u operacijskoj dvorani minimalno invazivnim kirurškim pristupom izvade se svi zaostali konci i drenira formirani apsces. Rasprava: Klasični kirurški zahvat je invazivan s mogućnošću propagacije infekcije prema zdravom tkivu te uz mogućnost pogreške u smislu nenalaženja svih zaostalih konaca uzročnika upalnog odgovora. Prikazom ovih dvaju slučajeva dokazali smo da, osim u dijagnostičke svrhe, ultrazvuk može poslužiti kao pomoć pri samom kirurškom postupku u cilju izvođenja minimalno invazivnog kirurškog zahvata. Zaključak: U prikazu slučaja upućuje se na potencijalnu vrijednost minimalno invazivne kirurške tehnike pod kontrolom ultrazvuka kojom se mogu izvaditi zaostali konci i drenirati nastali apsces u bolesnika.Aim: To evaluate the use of ultrasound in management of the long term complications after surgical procedure of the ruptured Achiles tendon. Case report: Authors report two cases of patients who developed tissue inflammation and abscess six and five years after surgery following rupture of the Achilles tendon. Ultrasound examination of the Achilles tendon confirmed abscess and foreign body (stitch) in both patients. A minimally invasive ultrasound guided technique was used for extracting all stitches and drainage of the present abscess in both patients. Discussion: The clasical surgical approach is an invasive procedure with high possibility of widespreading infection into the healthy tissue. There is also the possibility of not finding all stitches which cause inflammation. These two cases emphasize the use of ultrasound not only for diagnosis but also as a help, during the minimally invasive surgical procedure. Conclusion: In this case report we point out the potential value of the minimally invasive ultrasound guided surgery for extracting stitches and drainage of the present abscesses in both patients

Advantages of Intramedullar Fixation in Treatment of Congenital Tibial Pseudoarthrosis – A Case Report

This report describes a case of a 29-year old patient with congenital pseudoarthrosis of the distal tibia previously treated unsuccessfully by a conventional surgical method. Tibial congenital pseudoarthrosis is a rare disease characterized by segmental osseous weakness resulting in deformation of the bone and spontaneous fractures which progresses to a tibial nonunion. In our case we used intramedullary stabilization with bone grafting and six month after operation congenital pseudarthrosis of the tibia healed

RESULTS OF APPLICATION OF BASIC WORKPLACE SAFETY RULES ON THE REDUCTION OF WORK-RELATED INJURIES

Cilj ovog istraživanja je analizirati i usporediti prosječnu godišnju stopu ozljeda na radu u tekstilnoj i građevinskoj industriji za razdoblje od 1997. do 2006. godine. Za istraživanje ozljeda na radu uzeti su podaci iz četiri tekstilne i dvije građevinske tvrtke. U statističkoj analizi primijenjeni su hi kvadrat test i aritmetička sredina za procjenu rezultata. Uspoređen je broj ozljeda u obje gospodarske grane po danima u tjednu, po mjesecima i prema dobi dana. Rezultati istraživanja ukazuju da kontinuirana primjena preventivnih mjera zaštite na radu u znatnijoj mjeri može utjecati na smanjenje ozljeda na radu i produktivnost rada.SUMMARY: The purpose of this investigation is to analyze and compare the average annual rate of occupational injuries in the textile and the civil engineering industries for the period from 1997 to 2006. In order to investigate these occupational injuries, data was gathered from four textile and two construction companies. The chi-square test and the arithmetic mean were used as statistical tools in assessing the results. The numbers of injuries in both industry branches were compared by the day of the week, by the month and according to the time of day. The research findings indicate that the continuous use of preventive measures of occupational safety can considerably affect the reduction of occupational injuries and labor productivity

Impact of downtime pattern on mining machinery efficiency

In this paper, problem of mining machinery efficiency is considered through impact of different types of downtimes. New methodology is suggested based on comparison impact of mechanical and technological mining machinery time in fault (M-t, T-t) and mechanical and technological mining machinery downtime frequencies (M-f, T-f) on machine work done (W). Benchmarking analysis is conducted by pairing variables M-t-W, T-t-W, M-f-W and T-f-W, and determining relationships between observed variables. By comparing the increment of the cumulative downtime curve with the cumulative curve of the machine's operating volume, it can be assessed whether the observed downtime develops a concave or convex character of the operating volume cumulative curve, in respect to significant losses. Results indicate that the relationship between cumulative downtime curve and cumulative work done curve can successfully serve as a parameter for evaluating the impact of specific downtime on the efficiency of the machine. A multi-criteria analysis, namely, an analysis of the criteria - frequency and time spent in downtime for each of the observed causes of downtime, clearly determines the critical pattern of downtime on the efficiency of the observed machine