This paper identifies the adverse events occurring during the execution of water supply and sewerage systems construction. The basis for this paper is research conducted in 2010-2014 on the construction sites of water supply and sewerage systems located in the provinces of Lower Silesia and Opole. The research consisted of direct observations of construction sites and review of construction documentation. It showed that work stoppages on the examined construction sites were frequent. They were caused by violations of work discipline by the production employees, adverse weather conditions, and defects in the project documentation. The study demonstrated that in almost every case, these bad an adverse effect on the completion date and budget of the investment. The analyses show that in such important and expensive investments as water supply and sewerage systems, organizational structures in which a special role is assigned to middle-rank personnel should be adopted.
The text comprises the evaluation of relationship between the qualitative planning tools and the Irish housing policy in the pre-crisis period, during the crisis (2009-2013) and the recovery. The tools that affect housing are understood as spatial planning, including governmental regulations on densification of the development and the housing quality as well as the special tools such as the urban design. Those regulatory tools were deployed with aims to safeguard the sustainable and socially viable housing structures. The Irish case illustrates the considerable innovation in introducing new housing standards and challenges with their efficiency. This can be attributed to the lack of integration with other elements that shaped the market – financing and actions of the private market, low efficiency of planning or the lack of the scale effect for the model developments. Despite their drawbacks these tools are continuously being used, as their foundational principles are still valid.
The Stirling engine type alpha is composed of two cylinders (expansion space E and compression space C), regenerator that forms the space between the cylinders and the buffer space (under the pistons). Before the start-up and as a result of long-term operation, the average pressure in the working space (above the pistons) and in the buffer space is the same. However, in the initial phase of operation, the average pressure in the working space is different then the average pressure in the buffer space depending on the crankshaft starting position (starting angle). This, in turn, causes a large variation in the starting torque. An additional unfavorable factor caused by a large variation in the course of the indicated torque is the rotational speed variation and the formation of torsional vibrations in the drive system. After some time, depending on the quality of the engine piston sealing, the average pressure in the working and buffer space will equalize. The occurrence of the above-described phenomenon affects the selection of the starting electric motor, which can be significantly reduced, when the crankshaft starting position is optimized (the starting torque is several times greater than the average torque occurring in the generator operation mode). This paper presents the analysis of the impact of the crankshaft starting position on the course of the indicated torque and the resulting start-up energy. Starting the engine at an unfavorable position of the crankshaft may, in extreme cases, increase the starting torque even three times.
In view of the world’s recent changes in the mineral market, it is becoming increasingly important to ensure the sustainable and secure supply of raw materials, both within the European Union and in other high-developed countries. In response to this global challenge, as part of the European Commission’s Horizon 2020 Program for Research & Innovation, the 36-month INTRAW project was launched in February 2015 to foster international cooperation on raw materials. The EU-funded INTRAW project was set up to map and develop new cooperation opportunities related to raw materials between the EU and other technologically advanced countries, such as: Australia, Canada, Japan, South Africa and the United States. The first stage of the project was a review of conditions for the stable supply of raw materials from primary and secondary sources in selected countries: the United States, Canada, Australia, South Africa and Japan. The results of the work are two groups of comprehensive reports. The first of these is a broad contextual analysis of geological, environmental, political, technical -economic and social factors conducive to the effective management of mineral resources. The second group is operational reports, carried out in three thematic blocks: industry and trade, research and innovation, education. The analysis clearly shows that the basis for effective action in this area is a stable political, economic and institutional environment, which is friendly to mining and new entities wishing to invest in modern technologies, the exploration and exploitation of deposits. Investors are encouraged by tax regulations, sometimes also by direct government financial support and efficient licensing procedures. The well-defined protection of property rights, also for deposits is equally important. Selected aspects of a wide analysis of determinants of competitiveness for these countries were presented in the article below.
In order to improve the efficiency and ensure the security of power supply used in a mine, this paper mainly studies the quasi-resonant flyback secondary power supply and analyzes its operational principles based on the requirements of soft-switching technology. In accordance with the maximum energy of a short-circuit and the request of maximum output voltage ripple, this paper calculates the spectrum value of the output filter capacitor and provides its design and procedures to determine the parameters of the main circuit of power supply. The correctness and availability of this theory are eventually validated by experiments.
Due to different reasons a significant modal shift from railway to road transport took place over last decades. The basic reasons are pointed in the paper introduction together with contradicting transport policy taking into account environmental and economical challenges. Political vision to stimulate modal shift from road and air to railway cannot become true without achieving railway technical and operational interoperability. Paper describes wide range of technical barriers between individual intraoperable railway systems in civil engineering structures, traction power supply, control command and signalling and the ways, which are being applied to ensure stepwise converging of the technical solutions taking into account safety and technical compatibility, as well as other essential requirements, namely: reliability, accessibility, health and environment.
A 6 km long stretch of the coast of Calypsostranda between Skilvika and Josephbukta, situated on the western side of Recherchefjorden, was investigated. It is made of an accumulative marine terrace at a height of 2–8 m a.s.l. (terrace 1) and width of 40–180 m, divided by a cliffed section in the frontal moraines of Renardbreen. From the character and intensity of changes, the area was divided into 6 zones. The aim was to analyse the dynamics of changes within coastal zone from 1936 to 2007 and to characterise the influence of various morphogenetic factors (marine, fluvial, cryospheric). The important element of this study has been to determine sources and directions of sediment transport. The dynamics of changes of coastal zone in the Calypsostranda region was established from archival maps and precise GPS measurements for the periods: 1936–1960, 1960–1990, 1990–2000, 2000–2005, 2005–2006, 2006–2007. Comparing the extension of shoreline between 1936 and 2007 showed that there was more erosion than accumulation. Nearly 110 000 m 2 of the area of terrace 1 decreased, whereas about 77 000 m 2 appeared. The net balance for 1936–2007 was about −32 700 m 2 , on average over the whole length of the shoreline, it re − treated by 5.7 m (0.08 m a −1 ). The cease of sediment delivery in the extramarginal sandur fans area of Renardbreen caused intensification of marine processes, that made the shore − line retreat by over 100 m. Continuing sediment delivery from the Scottelva catchment, with contribution of material from erosion of the north end of the shoreline studies, caused the aggradation of coastal zone by over 60 m near its mouth.
The scope of the paper refers to long- and medium-run trends of labour supply in Poland. The main purpose is to determine current trends in the labour supply and its projections till the year 2050. In the theoretical part of the paper determinants of labour supply are considered. The projections are based on the population forecasts till 2050 made by the Central Statistical Office of Poland (CSO) and by the authors’ own simulations. Several variants of upper limit of working age and activity rates are taken into account. The population forecasts by the CSO indicate it will occur big decrease of working age population till 2050. The biggest decrease will refer to the group of working age 18–59/64 years and the lowest decrease in the age group 18–66 years. The analysis shows that the declines in labour supply in the years 2020–2050 will occur in all variants of working age population, the biggest decline in the variant assuming the age group 18–59/64 and the smallest decline – in the group 15–74 years. Retirement age is of big importance for the size of labour supply. This is why it is recommended to encourage older people to prolong their economic activity. It is also necessary to increase activity rates in the working age population.
The evaporation temperature is regarded as one of the major parameters influencing the organic Rankine cycle (ORC) efficiency. Majority of contributions in literature for ORC cycle analyses treat the heat source as if it had an infinite heat capacity. Such analyses are not valuable as the resulting temperature drops of the heat source needs to be small. That leads to the fact that the heat source is not well explored and in the case of waste heat utilization it can prove the poor economics of the ORC. In the present study cooperation of the ORC cycle with the heat source available as a single phase or phase changing fluids is considered. The analytical heat balance models have been developed, which enable in a simple way calculation of heating fluid temperature variation as well as the ratio of flow rates of heating and working fluids in ORC cycle. The developed analytical expressions enable also calculation of the outlet temperature of the heating fluid.
Industry 4.0 will affect the complexity of supply chain networks. It will be necessary to adapt more and more to the customer and respond within a time interval that is willing to accept the product waiting. From these considerations, there is a need for a different way of managing the supply chain. The traditional concept of supply chain as a linear system, which allows optimizing individual subsystems, thus obtaining an optimized supply chain, is not enough. The article deals with the issue of supply chain management reflecting demand behaviour using the methodology Demand Driven MRP system. The aim of the publication is to extend the knowledge base in the area of demand-driven supply logistics in the
The paper refers to planning deliveries of food products (especially those available in certain seasons) to the recipients: supermarket networks. The paper presents two approaches to solving problems of simultaneous selection of suppliers and transportation modes and construction of product flow schedules with these transportation modes. Linear mathematical models have been built for the presented solution approaches. The cost criterion has been taken into consideration in them. The following costs have been taken into account: purchase of products by individual recipients, transport services, storing of products supplied before the planned deadlines and penalties for delays in supply of products. Two solution approaches (used for transportation planning and selection of suppliers and selection of transportation modes) have been compared. The monolithic approach calls for simultaneous solutions for the problems of supplier selection and selection of transportation modes. In the alternative (hierarchical) solution approach, suppliers are selected first, and then transportation companies and their relevant transportation modes are selected. The results of computational experiments are used for comparison of the hierarchical and monolithic solution approaches.
The influence and the potential risk due to hidden faults of a relay protection system on power supply in distribution systems are paid more and more attention to. A probability analysis method is used to analyse fault characteristics and action mechanism of dominant faults, hidden misoperation and non-operation of the relay protection systems, and failure probability model of relay protection system is constructed and simplified. The effects of dominant faults, hidden misoperation and non-operation of the relay protection systems on the reduced power supply load power are analysed, and a probabilistic model for reduced power supply load power is constructed by three parts corresponding to dominant faults, hidden misoperation and non-operation. A probability calculation method of power supply risk occurrence due to hidden faults of relay protecttion system is proposed considering the fault probability of the relay protection systems, the frequency of the hidden faults occurring in operation period, the reduced power supply load power or load power outage, and the connection mode of the in-lines, out-lines and transformers in a substation. The feasibility and applicability of the proposed method for estimation of risk value probability of the relay protection systems is verified by two studied examples.
In the over 150 years of hydrocarbon history, the year 2017 will be one of the many similar. However, it will be a breakthrough year for liquefied natural gas. In Asia, China grew to become the leader of import growth, becoming the second world importer, overtaking even South Korea and chasing Japan. The Panama Canal for LNG trade and the “Northern Passage” was opened, so that Russian LNG supplies appeared in Europe. The year 2017 was marked by a dramatic shortening of the length of long-term concluded contracts, their shorter tenure and reduction of volumes – that is, it was another period of market commoditization of this energy resource. The article describes the current state of LNG production and trade till 2018. It focuses on natural gas production in the United States, Qatar, Australia, Russia as countries that can produce and supply LNG to the European Union. The issue of prices and the contracts terms in 2017 was analyzed in detail. The authors stress that the market is currently characterized by an oversupply and will last at least until mid–2020. Novatek, Total – Yamal-LNG project leaders have put the condensing facility at 5.5 million tons into operation. The Christophe de Margerie oil tanker was the first commercial unit to cross the route to Norway and then further to the UK without icebreakers and set a new record on the North Sea Road. In 2017, the Russian company increased its share in the European gas market from 33.1 to 34.7%. In 2017, Russia and Norway exported record volumes of „tubular” – classic natural gas to Europe (and Turkey), 194 and 122 billion m3 respectively, which is 15 and 9 billion m3 more natural gas than in 2016. The thesis was put forward that Russia would not easily give up its sphere of influence and would do everything and use various mechanisms, not only on the market, that it would simply be more expensive and economically unprofitable than natural gas. It was also emphasized that the pressure of the technically possible and economically viable redirection to European terminals of methane carriers landed in the American LNG, results in Gazprom not having a choice but to adjust its prices. The Americans, but also any other supplier (Australia?) can simply do the same and this awareness alone is enough for Russian gas to be present in Europe at a good price.
The article concerns safety of power supply for the final consumers, especially its two comprising elements, which are generation adequacy and distribution system reliability. Generation adequacy has been defined with Loss of Load Probability (LOLP), Loss of Load Expectation (LOLE) and Energy Not Supplied (ENS) indices. Conclusions from generation adequacy forecast prepared by ENSTO-E for Poland compared with other European countries for the years 2020 and 2025 have been discussed along with the resulting threats. Interruptions in energy supply have been characterised by power discontinuity indicator SAIDI. Finally, a reliability and adequacy analysis have been performed for different scenarios of the Polish power system operation in order to assess possibilities of using distributed generation as a backup power source. Based on a simulation model created using the DIgSILENT Power Factory software, the reliability and adequacy calculations have been performed with the probabilistic non-sequential Monte Carlo method and they are followed by a discussion of the obtained results.
Performance measurement system in supply chain management (SCM) has been receiving increasing attention by business organizations as a way to evaluate efficiency in supply chain activities. Assessing the performance of supply chain uncovers the gap between planning and actual performance as to trace the potential problems thus ascertain necessary areas for improvement. This research aims to investigate the application of performance measurement system in SCM as well as exploring its relationship with organization’s performance among Malaysian manufacturing firms. By utilizing the questionnaire method, respondents involved were requested to indicate the extent to which they use a number of 24 selected performance measures that are related to SCM. The results show that the majority of the observed manufacturing firms utilize specific performance measurement tools in evaluating the supply chain performance. The current performance measurement techniques, the Balanced Score Card is adopted by around a quarter of the total responding firms followed by Supply Chain Operations References Model – SCOR, which attracts total users of only a fifth of the total respondents. In particular, performance measures under customer service category recorded the highest number of usage followed by cost-based performance measures and operations management. The results of this investigation also unveil few major points that are important to be highlighted. Firstly, the obtained outcomes of this study bring to light the significant relationships between the utilization of supply chain performance measures under customer service, operations management and organizational performance. In addition, this study discovered a significant correlation between the size of the organization and the extent of use of supply chain performance measures and how these two variables positively correlated. Lastly, the findings also suggested that the performance measures for SCM has been playing a crucial role in enhancing the performance of the organizations and is increasingly operated as the firms grow in size. Based on the brief highlighted points listed above, it is not an exaggeration to say that this research contributes new information to the body of knowledge in performance measurement system in SCM and its associations with organizational performance.
The paper looks at the issues of operation safety of the national power grid and the characteristics of the national power grid in the areas of transmission and distribution. The issues of operation safety of the national transmission and distribution grid were discussed as well as threats to operation safety and security of the electricity supply related to these grids. Failures in the transmission and distribution grid in 2017, caused by extreme weather conditions such as: a violent storm at the night of 11/12.08.2017, hurricane Ksawery on 5–8.10.2017, and hurricane Grzegorz on 29–30.10.2017, the effects of which affected tens of thousands of electricity consumers and led to significant interruptions in the supply of electricity were presented. At present, the national power (transmission and distribution) grid does not pose a threat to the operation safety and security of the electricity supply, and is adapted to the current typical conditions of electricity demand and the performance of tasks during a normal state of affairs, but locally may pose threats, especially in extreme weather conditions. A potentially high threat to the operation safety of the national power grid is closely linked to: age, technical condition and the degree of depletion of the transmission and distribution grids, and their high failure rate due to weather anomalies. Therefore, it is necessary to develop and modernize the 400 and 220 kV transmission grids, cross-border interconnections, and the 110 kV distribution grid (especially in the area of large urban agglomerations), and the MV distribution grid (especially in rural areas). The challenges faced by the transmission and distribution grid operators within the scope of investment and operating activities, with a view to avoiding or at least reducing the scale of grid failures in the case of future sudden high-intensity atmospheric phenomena, are presented.
As experience shows the practical, reliable assessment and optimisation of total costs of logistical processes implemented in supply chains of foundry plants is a quite complex and complicated process, because it requires to enclose all, without exception, performed actions, including them in various reference cross-sections, systematic activities and finally transforming them in a totally homogenous collection. Only solid analysis and assessment of assortment management in logistical supply systems in foundry plants of particular assortment groups allows to lower the supply costs significantly. In the article the analysis and assessment of the newest implemented optimising algorithms are presented in the process stock management of selected material groups used in a production process of a chosen foundry plant. A practical solution to solve a problem of rotary stock cost minimisation is given as well as of costs while creating a stock with the usage of economical volume and value of order.
The proper description of circuits supplied from an asymmetrical and sinusoidal voltage source, in which line parameters are included, requires an adequate mathematical concept or theory. The authors of the publication present the mathematical concept of the currents’ asymmetrical components for three-phase four-wire systems, taking into account the impedance of the neutral conductor and the impedance of power transmission lines. In the new approach, four orthogonal current components were proposed in charge of its flow between the source and the load. The introduced distribution shows, regardless of the type of the voltage asymmetry (amplitude or phase), it is possible to set down the symmetrical active current and other components, i.e. reactive current, negative current and zero current, which will allow determining the reference current of the active filter.
The aim of the paper is to compare nitrate concentrations in samples of supply water as well as water from deep and dug wells located in the eastern region of Poland. Additionally, samples of bottled water (spring and natural mineral), certifi ed by the Institute of Mother and Child and the Children’s Memorial Health Institute, were subjected to analyses. On the basis of the obtained results, health risks related to the occurrence of methemoglobinemia in neonates and infants were evaluated. The risk analysis was performed according to the procedure recommended by the United States Environmental Protection Agency. Nitrate concentrations in the examined samples ranged from: 0.153–161.1 mg/l. The lowest concentration of nitrates was determined in the samples of bottled water, the highest being detected in the water from dug wells. It was found that nitrate concentration in samples of bottled and supply water did not pose any risk to the health of neonates and infants. The highest health risk related to methemoglobinemia occurs for neonates consuming water originating from dug wells. The risk decreases along with the age of an infant.
Along with the increase in the use of nonlinear electronic devices, e.g. personal computers, power tools and other electrical appliances, the requirements for uninterruptible power supplies are constantly growing. This paper proposes a method and deep analysis of results viable for checking how single-phase uninterruptible power supplies (UPSs) cope with nonlinear circuits under varying power loads in terms of electric energy quality.Various classes of single-phase UPS systems with different topologies were tested, for instance line-interactive and double conversion (online) single-phase UPS devices. Furthermore, measurements were carried out in view of a power source – loads were supplied both from a power grid and UPS built-in battery. Juxtaposition of the obtained results such as a THDU, THDI (Total Harmonic Distortion) percentage ratio of input/output voltage and current, a power factor and crest factor volume etc. of the tested UPS systems indicated major differences in their performance during laboratory tests.
This original paper deals with a new approach for the study of behavior in nonlinear regime of a new three-phase high voltage power supply for magnetrons, used for the microwave generators in industrial applications. The design of this system is composed of a new three-phase leakage flux transformer supplying by phase a cell, composed of a capacitor and a diode, which multiplies the voltage and stabilizes the current. Each cell. in turn, supplies a single magnetron. An equivalent model of this transformer is developed taking into account the saturation phenomenon and the stabilization process of each magnetron. Each inductance of the model is characterized by a non linear relation between flux and current. This model was tested by EMTP software near the nominal state. The theoretical results were compared to experimental measurements with a good agreement. Relative to the current device, the new systemprovides gains of size, volume, cost of implementation and maintenance which make it more economical.
Due to globalized business operations, companies in different economic sectors are part of complex supply chain networks. Their value-added processes comprise product and information flows, e.g. with a focus on manufacturing, service or trade. Until the final product is delivered to the end customer, it needs to pass many different processes in cooperating organizations. As a result, there a lot of business-to-business (B2B) interactions with crossenterprise transactions, often including cross-border communications and sometimes even cross-industry trades with technological and often cultural implications. Especially the interfaces of supply chain networks are prone to inefficiencies, misunderstandings and delays due to a lack of standardized B2B transactions, which leads to waste in form of rework, errors and mistakes. In addition, new customers are hard to find for the manufacturing or trading company, since potential customers are so far limited to a regional network. The advantages of extending the customer base still need to be explored by many organizations. This paper discusses the opportunities by streamlining the communication along supply chain networks in a general fashion and then describes the application in a B2B automotive retail business. A concept of a web-based trading platform, which provides a seamless service for all steps of a convenient and efficient used vehicle remarketing business, is developed. It includes all phases, like offering and price finding in a comprehensive online platform, which also covers further activities, such as logistic services, financial transactions, and a mandatory feedback loop. The suggested B2B vehicle-trading platform enables a quick turnover of each transaction, which is analyzed and optimized based on the application of cross-enterprise Value Stream Management.
The paper attempted to define the basis of city transformations that conform to the smart concept. The objective of the paper is to relate the concept of a smart city, which is quite frequently discussed in literature related to the subject, with functioning and development of the city’s economy, in a way that would allow monitoring economic processes taking place in the city, and also to find a response to the question as to the extent to which the smart city creates a new city economy. Does it expand the city economy by new elements, generate new economic mechanisms, allow the implementation of growth paths different than those to date? This objective is particularised by a description of selected issues of urban economics. With this in mind the paper discusses an approach to managing supply and demand on the basis of theoretical assumptions defined by Mudie and Cottam (1993) transposed on realities connected with provision of municipal public services in conditions of a smart city. Furthermore, sample solutions were presented related to the smart city, which reflect theoretical conclusions contained in the paper. The paper ends with a presentation of logics related to growing economy in a smart city. The economy of a smart city, ultimately an intelligent economy of the city, is created in a laminar way. Under the pressure of technological, social and political surroundings the city is permeated by social and culture intelligence, forming gradually a new economic quality. In the paper we emphasised that the concept of a smart city still remains a question of the future to a much bigger extent than one of the present time. A smart city slowly emerges from the combination of diverse megatrends and development trends characteristic for communities and economies of the second decade of the 21st century.
The supply chain of spare parts is the intersection between the supply chain, the after-sales and the maintenance services. Some authors have tried to define improvement paths in terms of models to satisfy the performance criteria. In addition, other authors are directed towards the integration of risk management in the demand forecasting and the stock management (performance evaluation) through probabilistic models. Among these models, the probabilistic graphical models are the most used, for example, Bayesian networks and petri nets. Performance evaluation is done through performance indicators. To measure the appreciation of the supply of the spare parts stock, this paper focuses on the performance evaluation of the system by petri nets. This evaluation will be done through an analytical study. The purpose of this study is to evaluate and analyze the performance of the system by proposed indicators. First, we present a literature review on Petri nets which is the essential tool in our modeling. Secondly, we present in the third section the analytical study of the model based on bath deterministic and stochastic petri networks. Finally, we present an analysis of the proposed model compared to the existing ones.