Improving efficiency in drive lines : an experimental study on churning losses in hypoid axle

The research concerns improvement of the power efficiency of lubricated components in automotive drivelines such as transmissions and axles. Meshed gear pairs, rolling bearings, seals and oil churning by rotating components immersed in the oil are studied. The purpose of the research is to explore the most effective way of improving the efficiency in drivelines, focusing on an axle comprising hypoid gears and a differential assembly. First, a study of the nature of losses affecting the efficiency of a simple spur gear box was carried out, and a model of friction and churning in a simple transmission was developed. Next, a detailed experimental study of oil churning losses in a hypoid axle from a four wheel drive road vehicle was carried out using the inertia run-down technique. To perform the above experiments, a new test rig for measuring oil churning losses was designed, manufactured and commissioned. The test rig allowed a wide range of speed and lubricant parameters to be explored and was designed by the author for tests available at different roll and pitch attitudes. In addition, an "extended" housing, consisting of a modified gear case that accepted the same internal components as the production axle but which had much greater internal clearances, was designed and manufactured. This enabled the effects of different casing geometry and of internal baffles to be studied. Additionally, the extension housing was modified to investigate the oil flow inside the housing through its one transparent side for the understanding of the effect of oil flow on churning losses. An investigation of design-related parameters influencing churning losses was carried out using the new test rig. Empirical equations for the churning losses, based on dimensional analysis, were developed to describe the test results. It was found that some combinations of baffles gave a significant reduction in losses. Supplementary tests were carried out using transparent windows to visualise the oil flow. These identified some of the mechanisms responsible for the reduction in churning loss and suggested a number of practical methods by which churning could be reduced without compromising the lubricant supply to remote components. It is argued that these innovations can contribute to improving fuel efficiency and limiting oil temperature rise in all-wheel-drive vehicles

A New Ultra-lightweight RFID Authentication Protocol using Merge and Separation Operations

Abstract Since Low-cost RFID tags have very limited hardware resources, it is difficult to implement an authentication protocol which uses heavy operations such as modern ciphers or hash functions. It has been presented some ultra-lightweight RFID authentication protocols for low-cost RFID tags by using very light operations. Recently, Jeon and Yoon proposed a new ultra-lightweight RFID authentication protocol. They defined and used the merge and separation operations. The merge operation can merge the bits from two bit strings and the separation operation is an inverse operation of the merge operation. However, we found that the protocol cannot serve correctly when the collision of tag pseudonyms is occurred. In this paper, we propose an improved authentication protocol that solves the problem. We show that the proposed protocol can resist various security attacks and is efficient enough to implement low-cost RFID tags

Complete Atrioventricular Block Secondary to Bortezomib Use in Multiple Myeloma

Bortezomib is an inhibitor of 26S proteasome, which is an effective treatment for multiple myeloma. The common adverse effects of bortezomib are asthenic conditions, gastrointestinal disturbances, and peripheral neuropathy. Here we describe a patient with dyspnea and general weakness because of complete atrioventricular block while receiving bortezomib. We immediately stopped bortezomib, and after inserting a permanent VDD pacemaker, the patients' symptoms disappeared

Low-resistance Ti/Al ohmic contact on undoped ZnO

We report a low-resistance ohmic contact on undoped ZnO using a promising contact scheme of Ti/Al. Specific-contact resistivity, as low as 9.0 x 10(-7) Omegacm(2), was obtained from the Ti(300 Angstrom)/Al(3,000 Angstrom) contact annealed at 300degreesC. It was found that TiO was produced, and the atomic ratio of Zn/O was dramatically increased after annealing at 300degreesC. This provides the evidence that a number of oxygen vacancies, acting as donors for electrons, were produced below the contact. This leads to the increase of electron concentration via the reduction of contact resistivity

Clinical outcomes and prognostic factors of mortality in liver cirrhosis patients on continuous renal replacement therapy in two tertiary hospitals in Korea

Background Data on liver cirrhosis (LC) patients undergoing continuous renal replacement therapy (CRRT) are lacking despite of the dismal prognosis. We therefore evaluated clinical characteristics and predictive factors related to mortality in LC patients undergoing CRRT. Methods We performed a retrospective observational study at two tertiary hospitals in Korea. A total of 229 LC patients who underwent CRRT were analyzed. Patients were classified into survivor and non-survivor groups. We used multivariable Cox regression analyses to identify predictive factors of in-hospital mortality. Results During a median follow-up of 5 days (interquartile range, 1–19 days), in-hospital mortality rate was 66.4%. In multivariable analysis, the Acute Physiology and Chronic Health Evaluation II (APACHE II) score (hazard ratio [HR], 1.03; 95% confidence interval [CI], 1.01–1.06; p = 0.02), Model for End-Stage Liver Disease (MELD) score (HR, 1.08; 95% CI, 1.04–1.11; p 35 mL/kg/hr (HR, 3.13; 95% CI, 1.62–6.05; p = 0.001). Subgroup analysis revealed that a CRRT delivered dose < 25 mL/kg/hr was a significant risk factor for in-hospital mortality among LC patients with a MELD score ≥ 30. Conclusion High APACHE II score, high MELD score, and low delivered CRRT dose were significant risk factors for in-hospital mortality. CRRT delivered dose impacted mortality significantly, especially in patients with a MELD score ≥ 30

Incidence and Predictive Factors of Benign Renal Lesions in Korean Patients with Preoperative Imaging Diagnoses of Renal Cell Carcinoma

The present study was performed to determine the incidence and predictive factors of benign renal lesions in Korean patients undergoing nephrectomy for presumed renal cell carcinoma on preoperative imaging. We analyzed the pathologic reports and medical records of 1,598 eligible patients with unilateral, nonmetastatic, and nonfamilial renal masses. Of the 1,598 renal masses, 114 (7.1%) were benign lesions, including angiomyolipoma in 47 (2.9%), oncocytoma in 23 (1.4%), and complicated cysts in 18 (1.1%) patients. On univariate analysis, the proportion of benign lesions was significantly higher in female patients, and in patients with smaller tumors, cystic renal masses, and without gross hematuria as a presenting symptom. When renal lesions were stratified by tumor size, the proportion of benign as opposed to malignant lesions decreased significantly as tumor size increased. On multivariate analysis, female gender, smaller tumor size, and cystic lesions were significantly associated with benign histological features. The findings in this large cohort of Korean patients show a lower incidence (7.1%) of benign renal lesions than those of previous Western reports. Female gender, cystic renal lesions, and smaller tumor size are independent predictors of benign histological features