Research on Initial Behavior of Screwed Lap Connections of Thin Plates – Experimental Tests and FEM Analysis

The paper continues the past research on the screwed thin-plate single-lap connections undertaken by the author. This re-search was focused on stressed skin diaphragm action, where it is essential to know values of connections behavior. Until now, initial stiffness is used for common engineering estimations. The main aim of this paper is to compare the experimental results of the shear tests conducted on the connections with the theoretical predictions of their initial behavior obtained from the FEM models. The experiments followed the Eurocode rules for design aided by testing and the European Convention for Constructional Steelwork (ECCS) recommendations. FEM parametric models are introduced as a consideration to use, taking into account screw threads and EPDM washers. In the technical literature, various techniques are described for the modelling of threaded connections. A modification to a known solution is applied in this analysis where a spiral thread is substituted by simple horizontal rings; this simplification allows use of symmetry in a static system, which is particularly desirable for large models such as those prepared in this paper. In contrast to the mentioned known solutions, the thread mod-el presented here has a triangular cross-section related to the geometry used in real screws. The numerical results correspond reasonably well to the test’s early stage measurements from the lab experiments and can be useful for initial stiffness examination (e.g. where no data is provided for a particular connector by a producer) or as a base to further research on the model

Fluffy fresh diaper service

Wisconsin\u27s new recycling law passed in 1990, will change the state\u27s throw-away habits. The goal is to cut down on more than six million tons of trash going into Wisconsin landfills and incinerators each year. This environmental awareness has rekindled the use of cloth diaper services, sending revenues up 38.5% in the United States in 1989 to 250 million dollars for the diaper service industry (Mehta, 1990). As an alternative to disposable diapers, Fluffy Fresh Diaper Service has been conceived to part of this market share by offering a cloth diaper laundry service for infants in the Fox Valley area. This report served to guide a go/no-go decision on Fluffy Fresh Diaper Service. Objectives were identified and monitored to determined if the business should be pursued. The objectives encompassed market share, customer loyalty, target markets, additional market expansion, and profit. Fluffy Fresh Diaper Service is a viable business opportunity. Customer convenience will be the focus of the business with a expected 10% rate of net profit based on sales each year for three years with the ultimate possibility of franchising

PRZEGLĄD WYBRANYCH METOD EWOLUCYJNYCH W OPTYMALIZACJI WIELOKRYTERIALNEJ

Since the mid-eighties we can see the development of methods that are based on a new method of creating dominated solutions. They lead to designate the ratings Pareto front mimicking the mechanisms created in the world of micro and macro-nature. Currently, the existing optimization methods can include: genetic algorithms, evolutionary algorithms using artificial immune systems, swarm and formic algorithms. The article presents few selected evolutionary optimization methods, including evolutionary algorithm, formic and swarm algorithms, and NSGA. The article also describes how the different algorithms work and their exemplary application.Od połowy lat osiemdziesiątych nastąpił rozwój metod, które bazują na nowym sposobie tworzenia rozwiązań niezdominowanych. Prowadzą one do wyznaczenia frontu ocen Pareto naśladując mechanizmy wytworzone w świecie mikro- i makro- przyrody. Aktualnie do istniejących metod optymalizacji zaliczyć możemy: algorytmy genetyczne, ewolucyjne, algorytmy stosujące sztuczne systemy immunologiczne, algorytmy rojowe oraz mrówkowe. W artykule zaprezentowano kilka wybranych metod optymalizacji ewolucyjnej, w tym  algorytm ewolucyjny, mrówkowy, rojowy oraz NSGA. Ponadto opisano sposób działania poszczególnych algorytmów oraz ich przykładowe zastosowanie

Self-organized Emergence of Navigability on Small-World Networks

This paper mainly investigates why small-world networks are navigable and how to navigate small-world networks. We find that the navigability can naturally emerge from self-organization in the absence of prior knowledge about underlying reference frames of networks. Through a process of information exchange and accumulation on networks, a hidden metric space for navigation on networks is constructed. Navigation based on distances between vertices in the hidden metric space can efficiently deliver messages on small-world networks, in which long range connections play an important role. Numerical simulations further suggest that high cluster coefficient and low diameter are both necessary for navigability. These interesting results provide profound insights into scalable routing on the Internet due to its distributed and localized requirements.Comment: 3 figure

DOBÓR URZĄDZEŃ KOMPENSACYJNYCH DLA FARMY WIATROWEJ PRZYŁĄCZONEJ DO SIECI 110 KV

Wind energy in Poland began to develop in the early 90s of the twentieth century, but its dynamic growth can be observed in subsequent years. At the end of 2014, the total installed capacity in wind farms in Poland amounted to 3 800 MW and continues to grow. The construction and installation of wind farms with high power brings with it a number of problems related to the compensation of the 110 kV cable lines of considerable length and the right type of compensation equipment. The article describes issues related to regulation of reactive power in wind farms and an analysis of individual compensation equipment used in wind energy.Energetyka wiatrowa w Polsce zaczęła się rozwijać na początku lat 90 XX wieku, jednak jej dynamiczny wzrost można zaobserwować w kolejnych latach. Pod koniec 2014 roku łączna moc zainstalowana w farmach wiatrowych w Polsce wynosiła ok. 3 800 MW i nadal rośnie. Budowa oraz instalacja farm wiatrowych o dużych mocach niesie za sobą szereg problemów związanych z kompensacją linii kablowych 110 kV, wyprowadzających moc z farmy wiatrowej o znacznych długościach oraz właściwym doborem urządzeń kompensacyjnych. W artykule opisano zagadnienia związane regulacją mocy biernej w farmach wiatrowych oraz dokonano analizy poszczególnych urządzeń kompensacyjnych wykorzystywanych w energetyce wiatrowej

Clinical spectrum and outcome of invasive mucormycosis in children and adults: Polish experience of the decade 2010–2019

No epidemiological data exist so far on invasive mucormycosis (IM) in Polish hematopoietic cell transplantation (HCT) and pediatric hemato-oncology (PHO) centers. The objective of this study was to analyze the incidence, clinical course, therapy, and outcome of IM in pediatric and adult patients undergoing HCT and children with hemato-oncological diseases in Poland. A total number of 12425 at-risk patients were retrospectively analyzed, and the period between 2010 and 2019 was included. Patients were analyzed in three groups: nontransplant children with malignancies, children undergoing HCT, and adults after HCT. Twenty-one patients were diagnosed with IM, including 15 children (10 non-HCT, 5 HCT) and 6 HCT adults. Proven IM was confirmed in 18 patients, probable in 2 patients, and possible in 1 patient. Proven IM was diagnosed in 7.1% of all patients with invasive fungal diseases (IFDs), including 8.1% among PHO patients, 5.4% among pediatric HCT patients, and 7.0% among adult HCT patients. Clinically, pneumonia was diagnosed in 10 (47.6%) patients, involvement of the paranasal sinuses was found in 3 (14.3%) patients, gastrointestinal disease was noted in 2 (9.5%) patients, and disseminated mucormycosis was found in 6 (28.6%) patients. The probability of overall survival in IM patients was 0.50 ± 0.11. Infection-related mortality (IRM) was 10% for pediatric nontransplant IM patients and 82% for transplant IM (pediatric + adult) patients ( = 0.004). Among the transplant patients, all adults died within 120 days. IRM for pediatric HCT patients was 60% ( = 0.038). The only prognostic factor was HCT, which adversely influenced survival in IM patients