Comparison of Oxygen Transfer Parameters Determined from the Steady State Oxygen Uptake Rate and the Non-Steady-State Changing Power Level Methods

In this study, a laboratory scale Univ. of Cape Town enhanced biological phosphorus removal process was operated under controlled conditions at a solids retention time of 15 days. Results are presented for the process performance and oxygen transfer parameters determined by applying the steady state oxygen uptake rate (OUR) and the changing power level (CPL) techniques, as per ASCE standard guidelines. The testing periods were temporally separated to eliminate interference of the tests. During the application of the CPL method, the sludge volume index gradually increased and higher values of the oxygen transfer rate and alpha were measured, in comparison to the data from the steady state OUR method, under similar process performance. Furthermore, the mass transfer rate decreased as the CPL method of testing continued. In contrast, the oxygen transfer parameters remained uniform during the time when the OUR method was applied. The data indicated that the CPL method resulted in higher and variable oxygen transfer parameters, even though the process performance remained unchanged. Therefore, a more rigorous evaluation of the CPL method is recommended to clarify the validity of the test.     

Evaluation and Predictive Model Development of Oxidative Stability of Biodiesel on Storage

Biodiesel comprises mono-alkyl esters of long-chain fatty acid methyl esters (FAME) derived from a renewable lipid feedstock. A major technical issue with the use of biodiesel is that it is more prone to oxidation during storage, when compared to petroleum fuel, due to the high content of polyunsaturated methyl esters that are easily oxidizable to compounds such as acids, aldehydes, and alcohols. Biodiesel (Jatropha and Pongamia) and antioxidants (Turmeric and butylated hydroxytoulene) were used for this study. We found that the acid value and viscosity for pongamia biodiesel increased significantly by 41.17% and 44.0% and that for jatropha biodiesel increased by 31.5% and 37.0%, respectively, after being stored for 3 months. The impact of antioxidants on the storage stability of biodiesel was examined according to the ASTM D4625 12-week procedure, and best results were found at a concentration level of 2500 ppm. The specific objective of this investigation is to develop models to determine the viscosity of biodiesel at any time “t” during long-term storage based on these experimental trials for upto 12 weeks. In addition, the models were used to predict the level of antioxidants that are to be added to biodiesel in order to minimize the effects of oxidative degradation during storage. The developed model recorded an adjusted R² of 0.86 and a modeling efficiency of 0.88.     

Experimental study on productivity enhancement of an improvised inclined solar still

Experimental studies are carried out on the inclined solar still with baffle plates for enhancing its performance. The baffles placed in the inclined solar still act as a solar collector which helps in increasing the contact time with solar radiation thereby raising the saline water temperature. Experiments are carried out during winter and early summer climate of Chennai, India. Experimental parameters, such as ambient temperature, solar radiation, glass temperature, water temperature and distillate output are recorded. Hourly productivity is found to be higher during sunny days. The estimated production of fresh water through analytical study is 3.50?kg/m² per day for a minimum mass flow rate of 0.0833?kg/min. The actual experimental yield is 2.793?kg/m² per day. Also, the inlet saline water temperature affects the yield and the latter is found to be highest at 48.5°C.     

An Authentication Protocol to Track an Object with Multiple RFID Tags Using Cloud Computing Environment

Wireless Personal Communications - In supply chain management applications, detection of a large object is made efficient by attaching multiple RFID tags in that object. Each part contains an RFID...     

Electrodeposition of eutectic Sn96.5Ag3.5 films from iodide–pyrophosphate solution

Electrodeposition of SnAg alloy films and the effect of additives like PEG-600 and hydrazine hydrochloride on the same were studied in KI–K₄P₂O₇ solutions. PEG-600 was found to adsorb on the electrode surface, resulting in strong reduction inhibition of tin pyrophosphate complex ions, but it does not affect the reduction of silver iodide complex. It was found that hydrazine hydrochloride acted as a reducing agent for Sn⁴⁺ species and greatly improved surface morphology and roughness of the films by preventing the formation of Sn dendrites during electrodeposition. Eutectic Sn_96.5Ag_3.5 was obtained from a plating solution that contained both PEG-600 and hydrazine hydrochloride as additives, at the deposition current density of 40 mA cm⁻². Stress measurements of the SnAg films showed that it was tensile. X-ray analysis of the deposit showed the presence of β-Sn and ?-Ag₃Sn phases in the eutectic SnAg film. The DSC profile of SnAg film gave the melting point as 222 °C.     

TURNING STUDIES OF DEEP CRYOGENIC TREATED P-40 TUNGSTEN CARBIDE CUTTING TOOL INSERTS – TECHNICAL COMMUNICATION

In the present work, coated tungsten carbide tool inserts of ISO P-40 grade were subjected to deep cryogenic treatment at ?176°C. Turning studies were conducted on AISI 1040 workpieces using both untreated and deep cryogenic treated tungsten carbide cutting tool inserts. The turning performance was evaluated in terms of flank wear of the cutting tool inserts, main cutting force and surface finish of the machined workpieces. The flank wear of deep cryogenic treated carbide tools was observed to be lower than that of untreated carbide tools in machining of AISI 1040 steel. The cutting force during machining of AISI 1040 steel was lower with the deep cryogenic treated carbide tools when compared with the untreated carbide tools. The surface finish produced on machined AISI 1040 steel workpieces was superior with the deep cryogenic treated carbide tools as compared to the untreated carbide tools.     

Particle entrainment by axisymmetric jets

The presence of particles can enhance or reduce the entrainment of an axisymmetric air jet. Measurements of particle entrainment in the 2 phase preheated jet were made by the Ricou and Spalding (1961) technique, and the results compared with theoretical estimates. Heating the jet stream improves the entrainment.     

Solution‐Processed Low Threshold Vertical Cavity Surface Emitting Lasers from All‐Inorganic Perovskite Nanocrystals

Recently, newly engineered all‐inorganic cesium lead halide perovskite nanocrystals (IPNCs) (CsPbX₃, X = Cl, Br, I) are discovered to possess superior optical gain properties appealing for solution‐processed cost‐effective lasers. Yet, the potential of such materials has not been exploited for practical laser devices, rendering the prospect as laser media elusive. Herein, the challenging but practically desirable vertical cavity surface emitting lasers (VCSELs) based on the CsPbX₃ IPNCs, featuring low threshold (9 µJ cm^?2), directional output (beam divergence of ≈3.6°), and favorable stability, are realized for the first time. Notably, the lasing wavelength can be tuned across the red, green, and blue region maintaining comparable thresholds, which is promising in developing single‐source‐pumped full‐color visible lasers. It is fully demonstrated that the characteristics of the VCSELs can be versatilely engineered by independent adjustment of the cavity and solution‐processable nanocrystals. The results unambiguously reveal the feasibility of the emerging CsPbX₃ IPNCs as practical laser media and represent a significant leap toward CsPbX₃ IPNC‐based laser devices.