Experimental and numerical analysis of a helical spring failure

Results of experimental and numerical analysis of a broken motor vehicle helical spring are presented in this paper. Location of the fracture is on a first active coil of the spring. Experimental part of the research employed optical microscopy that revealed fractured surface microstructure and allowed for detection of inclusions. Corroded fracture surface limited scanning electron microscopy examination (SEM). Nevertheless, corrosion pits on the edge of the spring wire which served as crack initiation points could be detected by SEM along with radiating ridges left by the fracture front that propagated to the opposite edge of the wire. Optical emission spectrometer with glow discharge source sample stimulation was used to determine material chemical composition that is adequate to spring steel 61SiCr7. Additionally, hardness test was performed and obtained value was used to derive maximum tensile strength of the steel. Experimentally collected data served as input for numerical analysis of helical spring. Finite element analysis of a helical spring model was performed. Stress distribution was determined and fatigue life of the undamaged helical spring predicted. Results were compared with those obtained analytical. Causes of failure are outlined assessing the results of the performed experimental and numerical analysis. Insufficient corrosion protection and excessive contact between the coils caused damage that developed from initial crack to final fracture of the spring. Results obtained by this research are valuable in understanding fracture behavior of helical spring mounted in suspension system of various motor vehicles. Given the presented results, further improvements of spring design can be made in order to reduce failures

Generalizations of Steffensen's inequality via Fink's identity and related results II

We use Fink's identity to obtain new identities related to generalizations of Steffensen's inequality. Ostrowski-type inequalities related to these generalizations are also given. Using inequalities for the Cebysev functional we obtain bounds for these identities. Further, we use these identities to obtain new generalizations of Steffensen's inequality for n-convex functions. Finally, we use the segeneralizations to construct a linear functional that generates exponentially convex functions.We use Fink’s identity to obtain new identities related to generalizations of Steffensen’s inequality. Ostrowski-type inequalities related to these generalizations are also given. Using inequalities for the Cebysev functional we obtain bounds for these identities. Further, we use these identities to obtain new generalizations of Steffensen’s inequality for n-convex functions. Finally, we use these generalizations to construct a linear functional that aenerates exvonentiallv convex functions

On generalizations of Ostrowski inequality via Euler harmonic identities

Copyright © 2002 L. J. Dedić et al. This work is licensed under a Creative Commons License.Some generalizations of Ostrowski inequality are given, by using some Euler identities involving harmonic sequences of polynomials.L. J. Dedić, M. Matić, J. Pečarić, and A. Vukeli

Kinetika i aktivnost leukocitne arilsulfataze A u osoba s dijagnozom cerebralne paralize

Activity and kinetics of arylsulfatase A (ASA, EC 3.1.6.8) were analyzed in leukocyte homogenates derived from patients suffering from cerebral palsy. Lower ASA activity was found in the patients\u27 leukocytes than in controls, as determined by spectrophotometry using chromogenic substrate p-nitrocatechol sulfate (p-NCS). Kinetic parameters, Km and vmax, for leukocyte ASA were determined from the dependence of initial reaction velocities on the p-NCS concentrations. A slight difference in Km values was found for leukocyte enzyme in cerebral palsy (0.26 mmol L-1) compared to the control (0.21 mmol L-1), whereas max-1 value for leukocyte ASA in disease reached only 58% of the control value. In addition, the presence of the most common mutations associated with ASA pseudodeficiency (N350S, 1524+95 A>G) and metachromatic leukodystrophy (P426L) was detected in all investigated patients. Changes in activity and kinetic parameters of leukocyte ASA in cerebral palsy are most probably related to the decrease of enzyme concentration; the detected mutations might at least partially contribute to the observed changes.Analizirane su aktivnost i kinetika arilsulfataze A (ASA, EC 3.1.6.8) u leukocitnim homogenatima osoba oboljelih od cerebralne paralize. Spektrofotometrijskim određivanjem aktivnosti ASA prema kromogenom supstratu p-nitrokatehol sulfatu (p-NCS) utvrđene su manje aktivnosti enzima u leukocitima oboljelih osoba. Kinetički parametri, Km i vmax, leukocitne ASA određeni su iz ovisnosti početne brzine reakcije o koncentraciji p-NCS. Utvrđena je manja razlika između Km vrijednosti enzima zdravih (0,21 mmol L-1) i oboljelih osobal (0.26 mmol L-1), dok je vrijednost vmax enzima iznosila 58% vrijednosti vmax enzima zdravih osoba. Također je u svih ispitanika s dijagnozom cerebralne paralize utvrđeno prisustvo najčešći mutacija povezanih s ASA pseudodeficijencijom (N350S, 1524+95 A>G) i metakromatskom leukodistrofijom (P426L). promjene aktivnosti i kinetičkih parametara leukocitne ASA u cerebralnoj parealizi najvjerojatnije su posljedica snižene koncentracije enzima; moguće je da nađene mutacije barem djelomično doprinose zapaženim promjenama

Analytical validation of therapeutic drug monitoring (TDM) on AxSYM Abbott analyzer

Introduction: Careful monitoring of drug concentration (therapeutic drug monitoring, TDM) is essential for a large number of drugs. The aim of this study was to evaluate analytical performance of Abbott AxSYM analyzer for therapeutic drug monitoring of theophylline, carbamazepine, pheno-barbital and valproic acid. Materials and methods: For the purpose of analytical validation following parameters were determined for all analytes: inaccuracy (bias), within-run and between-run imprecision and measurement uncertainty. Additionally, concentration of valproic acid was compared with the previously used analytical system (TDx FLx Abbott analyzer) for 30 patients\u27 samples. Results: Inaccuracy results (bias) were as follows: for theophylline from -3.66% to -5.84%; for carbamazepine -0.46% to 1.00%; for phenobarbital -1.83% to -8.08% and for valproic acid from -1.01% to -5.65%. The highest coefficient of variation (CV) for within run imprecision was observed for phenobarbital (7.07%) and the lowest for theophylline (2.71%). The highest CV for between run imprecision was observed for carbamazepine (4.73%) and the lowest for theophylline (2.94%). The highest measurement uncertainty was observed for phenobarbital assay (21.7%) and the lowest for carbamazepine (10.7%). Passing-Bablock regression analysis of valproic acid comparison on two analyzers showed statistically significant, but clinically insignificant deviation in slope of the regression equation (b = 1.121; 95% CI = 1.028-1.197); however the Cusum linearity test proved that there was a linear relationship between two methods. Conclusion: In conclusion, analytical validation fulfilled all previously established criteria and could be implemented in a routine laboratory work

RISK, RESISTANCE AND RESILIENCE OF HIGH-RISK WOMAN ABUSE SURVIVORS

Once understood as a personal concern, violence against women has been reconceptualized over the past thirty years as a societal problem (Standing Committee on Social Development, 1982). With increasing public attention to woman abuse, researchers have worked to understand what kinds of interventions might ameliorate this tragic phenomenon. Yet very few researchers have asked abused women for their views about interventions designed for their safety by social and police service agencies. This interview study explored five women's experiences of a Community Safety Protection Program (CSPP), a program intended to prevent future violence or deaths of "high risk" women at the hands of male partners or former partners. The central aim in the research was to situate the CSPP in the context of abused women's struggles and achievements: to examine how the CSPP contributes to their sense of safety, how it enables their resistance, and how it supports their strengths. The CSPP was found to have benefits beyond the stated intention of the program: it appears that the CSPP may be part of an important shift in the balance of power between a woman and her abusive former partner, changing the nature of her resistance and increasing her entitlement to safety. Interviews also reveal that women's risk of violence persists over time, and suggest careful attention to the match between women's circumstances and the length of time the program is offered. Interviews also highlighted a central paradox: the program's power to protect women can also work to oppress them. The positive impact the CSPP has on women's lives is undeniable; however changes in practice need to take place to mitigate the potential for disempowerment of the recipients of the CSPP.Master of Social Work (MSW

A comparative analysis of the corrosive effect of artificial saliva of variable pH on DMLS and cast Co-Cr-Mo dental alloy

Abstract: Dental alloys for direct metal laser sintering (DMLS) are available on the market today, but there is little scientific evidence reported on their characteristics. One of them is the release of ions, as an indicator of the corrosion characteristics of a dental alloy. Within this research, the difference in the elution of metals from DMLS and cast (CM) samples of Co-Cr-Mo dental alloy in saliva-like medium of three different pH was examined by inductively-coupled plasma mass spectrometry (ICP-MS). The obtained results show that the metal elution in artificial saliva from the DMLS alloy was lower than the elution from the CM alloy. The release of all investigated metal ions was influenced by the acidity, both from the DMLS and CM alloy, throughout the investigated period of 30 days. The change in acidity from a pH of 6.8 to a pH of 2.3 for the cast alloy led to a higher increase of the elution of Co, Cr and Mo from CM than from the DMLS alloy. The greatest release out of Co, Cr and Mo was for Co for both tested alloys. Further, the greatest release of all ions was measured at pH 2.3. In saliva of pH 2.3 and pH 4.5, the longer the investigated period, the higher the difference between the total metal ion release from the CM and DMLS alloys. Both alloys showed a safe level of elution according to the ISO definition in all investigated acidic environments

Questing with Grandma: Building Closer Families Through Intergenerational Video Gaming

While small and large technological miracles have undoubtedly made our lives easier, they have potentially also made a significant part of our daily social routine obsolete. People live in the same space but rarely spend quality time together, interacting and bonding. One of the solutions to diminishing family relationships may lie in the technology itself—video games. Previous research having shown the sociability of video games, and in this study, we examined their potential in creating closer family relationships, especially among different generations. Participants (n = 183), mainly grandparents and grandchildren, were asked to play video games together over a period of six weeks. Participants completed a modified version of the self-other overlap, self-disclosure, and relationship closeness inventories before and after the treatment and responded to a series of open-ended questions post-treatment. Results indicate a significant increase in the inclusion of other in the self, as well as an increase in breadth and depth of self-disclosure for both younger and older adults. A comparison group (n = 88), comprising also mostly grandparents and grandchildren, was tasked with having conversations either face-to-face or in a mediated setting. The comparison group completed the same questionnaires, with results indicating a significantly smaller increase in the inclusion of other in the self and depth of self-disclosure, while breadth of self-disclosure experienced the same increase as in the gaming group. The findings suggest that video games can provide a platform for family communication, resulting in the rejuvenation and maintenance of intergenerational relationships. Gathering around a novel shared activity, both younger and older adults found new ways of connecting to their family members, whether through more frequent conversations, broader selection of topics, shared subjects, or pure entertainment