Weibull approach to brake pad wear analysis in the Nigerian market

In this study, we evaluated the wear properties of four brands of brake pad available in the Nigerian market. In particular, we assessed the tribo performance and service life of the brake pads. We purchased four commercial brands of brake pads used in light duty cars and coded them as AU, SN, TY and SM, respectively. A small piece of the brake pad lining materials was carefully chiseled from the back plates to obtain samples for the experiments. We conducted Brinell hardness tests using a tensometer and a pin-on-disc test rig to determine the coefficient of friction and the wear characteristics of the materials. We then correlated the wear on each set of brake pads with the running time and used Weibull’s equation to determine average service life. Sample TY exhibited the highest hardness value (29.09) and sample SN the lowest (10.05). The determined coefficients of friction ranged between 0.3–0.36, with sample AU exhibiting the lowest value and sample SM the highest. Sample SN showed the lowest wear rate of 3.53 × 109 g/min, while the wear rates of samples TY, AU, and SM were 5.64 × 108, 8.19 × 109, and 2.10 × 108 g/min, respectively. The relative service life of samples SN, TY, and AU were similar, with average values of 2778.09, 2725.41, and 2717.34 min, respectively, and SM had a relatively low service life (2017.82 min). We conclude that the overall performances of Nigerian brake pads do not meet all the specifications for friction materials used in road vehicle brake linings and pads

Evidence of Polarons and Bipolarons in a Chemically Pressurized Nanoparticle Bi2Ba2Tb0.5Cu2O4+y

Previous researches on underdoped and overdoped Bi-2212 superconductor have shown that its mechanism follows the polarons-bipolarons theory of superconductivity. In this study, a chemically pressurized Bi-2212 compounds was synthesized and characterized. It was observed that phase analysis reveals the unique route of electron flow within the polycrystalline sample. The transmission electron microscopy (TEM) shows the presence of static and dynamic localizations that proves the possibly presence of Bose-Einstein condensation of inter-site bipolarons. This study on chemically pressurized Bi2Ba2Tb0.5Cu2O4+y compound has shown that the generation and dynamics of polarons and bipolarons are associated to the pentavalent post-transition nature of bismuth

Learning valued relations from data

Driven by a large number of potential applications in areas like bioinformatics, information retrieval and social network analysis, the problem setting of inferring relations between pairs of data objects has recently been investigated quite intensively in the machine learning community. To this end, current approaches typically consider datasets containing crisp relations, so that standard classification methods can be adopted. However, relations between objects like similarities and preferences are in many real-world applications often expressed in a graded manner. A general kernel-based framework for learning relations from data is introduced here. It extends existing approaches because both crisp and valued relations are considered, and it unifies existing approaches because different types of valued relations can be modeled, including symmetric and reciprocal relations. This framework establishes in this way important links between recent developments in fuzzy set theory and machine learning. Its usefulness is demonstrated on a case study in document retrieval

Pharmaceutical Formulation Facilities as Sources of Opioids and Other Pharmaceuticals to Wastewater Treatment Plant Effluents

Facilities involved in the manufacture of pharmaceutical products are an under-investigated source of pharmaceuticals to the environment. Between 2004 and 2009, 35 to 38 effluent samples were collected from each of three wastewater treatment plants (WWTPs) in New York and analyzed for seven pharmaceuticals including opioids and muscle relaxants. Two WWTPs (NY2 and NY3) receive substantial flows (>20% of plant flow) from pharmaceutical formulation facilities (PFF) and one (NY1) receives no PFF flow. Samples of effluents from 23 WWTPs across the United States were analyzed once for these pharmaceuticals as part of a national survey. Maximum pharmaceutical effluent concentrations for the national survey and NY1 effluent samples were generally <1 μg/L. Four pharmaceuticals (methadone, oxycodone, butalbital, and metaxalone) in samples of NY3 effluent had median concentrations ranging from 3.4 to >400 μg/L. Maximum concentrations of oxycodone (1700 μg/L) and metaxalone (3800 μg/L) in samples from NY3 effluent exceeded 1000 μg/L. Three pharmaceuticals (butalbital, carisoprodol, and oxycodone) in samples of NY2 effluent had median concentrations ranging from 2 to 11 μg/L. These findings suggest that current manufacturing practices at these PFFs can result in pharmaceuticals concentrations from 10 to 1000 times higher than those typically found in WWTP effluents

Characterisation of Pulverised Palm Kernel Shell for Sustainable Waste Diversification

The paper presents a report on the physico-thermal properties and elemental composition of pulverized palm kernel shell to enhance its use in engineering applications. Clean palm kernel shell were dried, milled and screened to obtain particles 0.23 mm mean diameter. Experiments were conducted to evaluate the physical and thermal properties of the pulverized palm kernel shell and its differential thermal analysis. Its elemental composition was determined by X-Ray Fluorescent analysis. Test results showed that pulverized palm kernel shell consist mainly of non-ferrous metals. Its bulk density was 560 kg/m 3; specific gravity, 1.26. Its thermal properties were characterized by thermal conductivity of 0.68 W/m K; specific heat capacity, 1.98kj/kg K, and phase change at 101.4 0 C. The report established significant potentials in the diversification of palm kernel shell from waste to fuel in improved combustion systems and as a future element in biomaterial composites