31 research outputs found
An Attempt at Evaluation of the Remnant Influence On the Occurrence of Seismic Phenomena in a Room-and-Pillar Mining System with Roof Deflection
No full textAbstract
Experience gained until now underground mining worldwide and in Poland indicates that remnants may have an impact on the occurrence of seismic phenomena. Remnants are stress concentration sites encompassing both the deposit and the layers of rock mass located above and below the undisturbed rock. In the case where stresses in the remnant exceed its strength, it may collapse, and under unfavourable geomechanical conditions, stress-induced rockburst may occur. Remnants may also cause breaking of strong roof layers above their edges, which results in the occurrence of high-energy shocks (Salustowicz [30], Adach [3], Adach and Butra [4]). This article presents the possibility of utilizing numerical modeling to evaluate the influence of remnant upon the occurrence of seismic phenomena. The results of numerical calculations performed for a model room-and-pillar mining system with roof deflection under the conditions of copper ore mines in the Legnica-Głogów Copper District (LGOM) are presented. Numerical calculations in a plane strain state were performed by means of Phase2 v. 8.0 software for the analyzed mining system in which remnant was left behind. The results of numerical modeling showed that sudden fracturing of roof layers above the mined out space may occur on the edge of the remnant. This may cause a shock with very high energy, and under the appropriate conditions, this may lead to the rockburst phenomenon.</jats:p
Mining operations conducted close to mined-out and yelding zones in a light of the practical experience and numerical modeling
No full textNa podstawie analizy dotychczasowych doświadczeń oraz wyników modelowania numerycznego przedstawiono zagadnienie zagrożenia tąpaniami i zawałami w przypadkach prowadzenia rozcinki w kierunku zrobów i stref upodatnionychBump and roof fall hazard potential is assessed based on the practical observations and numerical (FEM) modeling of mining operations conducted near the already mined-out and/or yielding zones
Planting Date and Night Break Treatment Affected Off-Season Flowering in Curcuma alismatifolia Gagnep
No full textVolume: 59Start Page: 173End Page: 18
Problematyka wyznaczania wielkości filarów oporowych wyrobisk kapitalnych w głębokich kopalniach rud miedzi
No full textThis article describes stability issues of main excavations in deep copper mines in Poland, from the perspective of mining work safety. To protect main transportation and ventilation routes, parts of rock are left untaken to form so-called protective pillars. The problem was to determine the size of main excavations protective pillars in deep underground copper mines in which provide stability of main excavations. The results of numerical simulations of the stability of protective pillars under specific geological and mining conditions are presented, covering: underground depth and width of protective pillar, number, size and layout geometry of protected excavations, as well as the impact of parameters of surrounding gob areas. Problem was solved applying numerical simulations based on the finite element method which were performed in a plane state of strain by means of Phase2 v. 8.0 software. The behavior of the rock mass under load was described by an elastic-plastic model. The Mohr-Coulomb criterion was used to assess the stability of the rock mass. The results of numerical modeling have practical applications in the designing of protective pillars primarily in determining their width. These results were used to prepare new guidelines for protective pillars in Polish copper mines in the Legnica-Glogow Copper District.W artykule pisano problematykę stateczności wyrobisk kapitalnych w głębokich kopalniach rud miedzi w Polsce, która jest bardzo ważnym zagadnieniem w aspekcie bezpieczeństwa prowadzonych robót górniczych. W celu ochrony głównych dróg komunikacyjnych i wentylacyjnych pozostawia się fragmenty calizny tworzące tak zwane filary oporowe. Następnie przedstawiono wyniki symulacji numerycznych stateczności filarów oporowych w określonych warunkach geologiczno-górniczych ich użytkowania, które objęły: głębokość zalegania i szerokość filara, liczbę i wielkości oraz geometrię rozmieszczenia wyrobisk chronionych, a także oddziaływanie parametrów pól zrobów w otoczeniu. Symulacje numeryczne wykonano w płaskim stanie odkształcenia za pomocą programu Phase2 v. 8.0, w oparciu o metodę elementów skończonych. Zachowanie górotworu pod obciążeniem opisano modelem sprężysto-plastycznym. Zastosowano kryterium wytrzymałościowe Coulomba-Mohra. Wyniki modelowania numerycznego mają zastosowanie praktyczne przy projektowaniu filarów oporowych. Zostały wykorzystane przy opracowaniu nowych wytycznych dla filarów ochronnych w polskich kopalniach rud miedzi w Legnicko-Głogowskim Okręgu Miedziowym
Metody analizy makrootoczenia
No full textZdigitalizowano i udostępniono w ramach projektu pn. Rozbudowa otwartych zasobów naukowych Repozytorium Uniwersytetu w Białymstoku, dofinansowanego z programu „Społeczna odpowiedzialność nauki” Ministra Edukacji i Nauki na podstawie umowy SONB/SP/512497/2021.R. U. Ayres, Prognozowanie rozwoju techniki i planowanie długookresowe, PWE, Warszawa 1973.K. Bartusik, P. Cabała, Metoda scenariuszy w planowaniu strategicznym, "Przegląd Organizacji" 1997, nr 2.J. Butra, A. Janowski, J. Kicki, S. Siewierski, K. Wanielista, Przedsiębiorstwo i jego otoczenie w gospodarce rynkowej, Wyd. IGSMiE PAN, Kraków 1999.Gierszewska, M. Romanowska, Analiza strategiczna przedsiębiorstwa, PWE, Warszawa 1994.W. Kasprzak, K. Pele, Wyzwania technologiczne - prognozy i strategie, Wydawnictwo Profesjonalnej Szkoły Biznesu, Kraków 1998.W. Kopaliński, Słownik wyrazów obcych i zwrotów obcojęzycznych, Wiedza Powszechna, Warszawa 1989.H. Kreikebaum, Strategiczne planowanie w przedsiębiorstwie, Wydawnictwo Naukowe PWN, Warszawa 1996.H. Krogh, Blick nach vorn, "Manager" nr 11, 1995, "Marketing i Rynek" 1996, nr 1.Leksykon marketingu, J. Altkorn, T. Kramer (red.), PWE, Warszawa 1998.M. Moszkowicz, Luki strategiczne - statyczna i dynamiczna, "Przegląd Organizacji" 1999, nr 9.Prognozowanie w zarządzaniu przedsiębiorstwem, M. Cieślak (red.), Wyd. AE im. O. Langego we Wrocławiu, Wrocław 1991.M. Romanowska, Strategie rozwoju i konkurencji, Centrum Informacji Menedżera, Warszawa 1998.Z. Sapijaszka, Restrukturyzacja przedsiębiorstwa. Szanse i ograniczenia, Wydawnictwo Naukowe PWN, Warszawa 1997.Zarządzanie strategiczne. Koncepcje, metody, R. Krupski (red.), Wyd. AE im. O. Langego we Wrocławiu, Wrocław 1998.546
Analysis of ore exploitation process and future plans in "G-7/5" panel in Rudna Cooper Mine
No full textScharakteryzowano warunki geologiczno-górnicze prowadzonej eksploatacji, występujące w rejonie pola G-7/5. Opisano przebieg robót górniczych od momentu rozpoczęcia eksploatacji w 2002 r. Przeanalizowano wyniki prowadzonych badań i obserwacji zachowania się górotworu oraz dokonano oceny stanu zagrożenia sejsmicznego w polu. Złoże rud miedzi w polu G-7/5, zlokalizowane jest na głębokości około 870 m, w skrzydle wiszącym uskoku "Biedrzychowa". W polu wydzielono trzy bloki eksploatacyjne. Bardzo trudne warunki geologiczno-górnicze w polu, zwłaszcza w bloku "A", powodowały wielokrotne zmiany kierunku prowadzenia robót, w tym na zroby i strefy upodatnione. Obecnie prowadzone są roboty likwidacyjne w bloku "A" i roboty rozcinkowe w bloku "B", które uruchomiono w sierpniu 2010 roku. Ze względu na poziom aktywności można wyróżnić trzy okresy podczas prowadzonej eksploatacji od października 2009 do września 2010 roku, które odpowiadają specyfice prowadzonych robót wybierkowych oraz stosowanej profilaktyce zagrożenia sejsmicznego. Lokalizacja ognisk silnych wstrząsów wskazuje, że większość z nich występowała w liniach uskoków, przebiegających przez strefę roboczą pola G-7/5 oraz na krawędziach prowadzonej rozcinki złoża. Dotychczasowej eksploatacji towarzyszył stosunkowo wysoki poziom zagrożenia tąpaniami i zawałami, głównie ze względu na zaangażowanie tektoniczne.In the paper geological and mining technology conditions in "G-7/5" panel of Rudna Cooper Mine was described. The mining process started in 2002 is presented as well. The results of rock mass observations and measurements were characterized and seismic hazard in "G-7/5" panel was evaluated. Ore body in "G-7/5" panel is located at a depth of 870 m in the downthrown side of "Biedrzychowa" fault. "G-7/5" panel is composed of three smaller excavation blocks. Hard geological and mining conditions in this panel, especially in block "A", often result in mining direction changes e.g. toward old workings and yielding zones. At present in block "A" liquidation works are carried out. In block "B" face-entry drivage was started in August 2010. Depending on activity level, during mining in that area between October 2009 and September 2010, three different periods can be distinguished. They correspond with the specific character of mining works and prevention methods against seismic activity hazard. Location of mining tremors indicate that many of them occurred in faults lines running through the working area in "G-7/5" panel and on the block development edges. Due to tectonic dislocations in this area, mining in "G-7/5" panel was connected with relatively high level of bumps and roof falls hazard
Fluctuating fortunes of a collective entreprise: The case of the Agroforestry Tree Seeds Association of Lantapan (ATSAL) in the Philippines
No full text"The Agroforestry Tree Seeds Association of Lantapan (ATSAL) in Bukidnon province, southern Philippines was organized in 1998, facilitated by the World Agroforestry Centre (ICRAF). Farmers were trained on germplasm collection, processing and marketing of agroforestry tree seeds and seedlings. ATSAL has been marketing various tree seeds and seedlings with apparent success, and has provided training on seed collection and nursery management to farmers, government technicians, and workers from non-government organizations (NGOs). This paper reports on the initial results of an on-going study to assess the effectiveness of ATSAL's marketing strategy, including group dynamics, and the issues and challenges the group faces. It was found that during the first two years, ATSAL's market share of greatly demanded timber tree species increased significantly, thus helping to disseminate widely these important species among farmers. ICRAF's technical back-up was an advantage, increasing the Association's market credibility. Subsequently, ATSAL extended its market to the central Philippines, but failed to meet the demand for seeds due to organizational limitations. Market competition exists, where a nonmember was able to take a larger market share than was the group. Nonetheless, ATSAL has established its name as a viable community-based seed and seedling producer, maintaining a stronghold in local and regional markets. Collective action is important for smallholders to break in, and gain market access, but is unlikely to sustain without effective leadership and some facilitation (in some cases even ongoing), thus requiring expenditures on repairs and maintenance through continuous technical and leadership training for the collective, and technical back-up and facilitation by an intermediary. Finally, facilitating smallholder collective action is essentially an arduous task, requiring the supporting agency to hold a firm grasp of market realities, to invest in the maintenance of collective action, to provide continuous technical back-up, and to ascertain the conditions that make collective action succeed." authors' abstractCollective action, Niche marketing, Agroforestry seeds, Community-based entreprise,
Comparison of Mechanical Properties of Carbon Fibre and Kaolin Reinforced Polypropylene Composites
No full textThis study aims to evaluate potential methodologies for improving the performance of polypropylene (PP) matrix compositesby the addition of carbon fibre and kaolin fillers, processed using a twin screw extruder, and compare them with neat PP. The effect offiller types and loading was investigated on mechanical properties such as the tensile modulus, flexural modulus, and impact strength,evaluated by using universal testing systems. Of the two types of composites, carbon fibre reinforced composites gave the bestperformance. The results showed that the addition of 30 wt% of short carbon fibre to neat PP raised the tensile modulus and flexuralmodulus by 219% and 280%, respectively, compared to neat PP itself. Also, the elongation at break was reduced by 87-96% comparedto neat PP, which is attributed to such fillers restricting the chain mobility of polymer molecules. Addition of kaolin has also resulted inimproved tensile and flexural modulus up to 42% and 41%, respectively, from that of the neat PP. Izod impact test showed that theaddition of kaolin also improves impact strength by up to 10% at low content of kaolin. However, the impact strength was reduced withincreasing kaolin content above 20% by weight, due to the agglomeration of kaolin particles. For PP/carbon fibre composites, the impact strength slightly increased when increasing the carbon fibre content from 10 wt% to 20 wt%, whereas it slightly dropped when increasing to 30 wt%. Based on these results, overall, the addition of carbon fibre and kaolin from 10-30 wt% significantly improves the tensile and flexural modulus properties. These fillers can be considered as promising reinforcing materials to increase the performance of thermoplastics. These type of composite systems may encourage commodity thermoplastics to be applied for high-end applications at a significant rate in the near future
Making market information services work better for the poor in Uganda:
No full text"There is growing pressure for farmers in countries such as Uganda to accelerate their efforts to commercialize production in the face of increasing market competition from neighboring countries and across the world. To assist farmers, a new generation of low cost market information services is being developed that takes advantage of information and communication technologies such as FM radios, mobile phones, and internet-based communications systems, to enable farmers to monitor and adjust to dynamic market conditions in local, national, and export markets. Although there is much interest in market information from farmers, other market chain actors, and service providers, there is skepticism from funding agencies to support such services over the long term, due to past failures. This study therefore aims to evaluate how farmers access and use market information to improve their market decision making. It also evaluates whether there are any advantages of collective action in using market information to improve marketing decisions. This is considered an important point of analysis as virtually all extension plans in Uganda currently use farmer groups as key element of their learning and intervention strategies. Survey results found that all farmers interviewed were able to access market information through radio and mobile phones. In Uganda, up to 94 percent of farmers interviewed owned a radio and 25 percent of farmers owned mobile phones. Up to 52 percent of farmers indicated that receiving Market Information Services (MIS) had a positive impact on their business, and 39 percent stated that it had a lot of impact in terms of decision making and stabilizing incomes." authors' abstractMarket Information Services, Group Marketing, Collective action, FM Radio, Mobile Phone, SMS, income,
