Improving Mining Performance for Internet Code Search Engines

To aid programmers in searching for code on the Internet, researchers and developers have created code search engines. These search engines use ranking algorithms to sort their results based on properties of the code. However, obtaining the properties to use a ranking algorithm requires a resource-intensive process, including downloading, parsing, analyzing, and indexing large amounts of code. Additionally, few guidelines exist for reducing the resources needed for this process without affecting the performance of the ranking algorithm. We explore two techniques for improving the process of mining code from the Internet for code search engines. First, we introduce What-If Ranking Analysis, a novel technique that attempts to find cheaper versions of a ranking algorithm by reducing the number of properties required when ranking. Second, we modify the original Beowulf cluster to optimize on network throughput instead of CPU performance to examine whether the modified cluster can outperform a single high-performance server in mining and uploading code for use in a code search engine. Our findings show that more efficient ranking algorithms exist that perform as well as the original ranking algorithm while reducing the time spent mining by 44% and reducing the disk space used for storage by 41%. Further, we find that the modified Beowulf cluster mines and processes code three times faster than a high-performance server at approximately the same cost

Turbulent Jet-Assisted Microfiltration for Energy Efficient Harvesting of Microalgae

For energy-efficient harvesting of microalgae using a hollow fiber membrane, a turbulent jet was implemented to induce local high crossflow velocity near the membrane surface for fouling reduction during microfiltration. The performance of the turbulent jet-assisted module was evaluated and compared to that of a control group that represented other types of flow conditions including the conventional-type hollow fiber membrane module. When assisted by the turbulent jet, permeate flux at the steady-state increased by 126% and the specific energy for filtrating out a unit volume of permeate was reduced by 38% relative to the conventional type. In the results of a computational fluid dynamics analysis, the wall jet created after impingement of the jet flew along the membrane surface with a reduced boundary layer, and it is expected that this provided a scouring phenomenon. Shear stress on the membrane surface increased 3.7-fold on average, and was highest at the point of impingement. With regard to energy efficiency, concentrating on increasing the local fluid velocity near the membrane via turbulent jets rather than increasing the entire feed recirculation is more practical to improve the filtration performance for microalgae harvesting with low power consumption

Solvent Screening and Process Optimization for High Shear-Assisted Lipid Extraction from Wet Cake of Nannochloropsis Sp.

Microalgae are regarded as a promising feedstock for biofuels and value-added products but still suffer from an inefficient lipid extraction process. In the present study, a simple and energy-efficient extraction method is demonstrated to extract oil directly from the wet cake (260 g/L) of Nannochloropsis sp. with an assist from the high shear mixer (HSM). After the initial solvent screening, the composition of co-solvent and operating conditions were optimized according to lipid composition and extraction yield. The high shear-assisted extraction process was found to achieve 83% lipid extraction yield (94% for EPA) in 5 min and 95% yield (100% for EPA) in 30 min with minimal amounts of solvents (0.9 ml hexane, 0.39 ml ethanol, and 0.057 ml sulfuric acid for 1 g of wet cell) at 8000 rpm, 55 °C. In comparison with various two-step wet extraction methods, the HSM offers the most economical extraction in terms of specific energy consumption of 1.38 MJ/kg dry cell. Therefore, the HSM can be considered as an attractive alternative to conventional extraction methods, providing a new paradigm of wet extraction for microalgae

Evaluation of Particle Bounce in Various Collection Substrates to be Used as Vaporizer in Aerosol Mass Spectrometer

<div><p>The determination of the collection efficiency (CE) of particles during transport, vaporization, and ionization in the aerosol mass spectrometer (AMS), which uses vaporizer to evaporate non-refractory particles with subsequent ionization, is important for accurately quantifying the concentrations of chemical constituents. Particle bounce in the vaporizer can be considered as one of the most important parameters influencing the CE of particles. Substrates with various shapes (flat, cylindrical, reverse-conical, cup, trapezoidal, and reverse-T), materials (stainless steel, copper, tungsten, and molybdenum), pores with average sizes of 0.2, 1, 5, 20, and 100 μm, and mesh with a size of 79 μm, which can be a possible candidate for the vaporizer in the AMS, were constructed. Bounce fractions of sub-micrometer particles (polystyrene latex, oleic acid, and dioctyl phthalate) were determined using the differential mobility analyzer (DMA)-impactor technique under a constant impact velocity. For the porous substrate, the particle bounce fraction significantly decreased with increasing pore size and porosity, but there was an upper limit for the pore size above which the particle bounce fraction no longer decreased significantly (i.e., the rebounded particles successfully escaped from the pores). The mesh substrate also had a lower particle bounce fraction than the flat substrate. Among the tested materials, the copper substrate having the lowest hardness and elasticity had the lowest particle bounce fraction. In addition, the reverse-T shape substrate having more available surfaces for particle entrapment led to the reduction of particle bounce fraction. In terms of phase, the liquid particles had lower particle bounce fractions than the solid particles. Our results suggest that the vaporizer in the AMS should provide traps for multiple collisions of the rebounding particles with an appropriate porosity or mesh and should be made of low-hardness materials to minimize particle bounce.</p><p>Copyright 2015 American Association for Aerosol Research</p></div

Osteonecrosis in Korean Paediatric and Young Adults with Acute Lymphoblastic Leukaemia or Lymphoblastic Lymphoma: A Nationwide Epidemiological Study

Osteonecrosis (ON) is a serious complication of acute lymphocytic leukaemia (ALL) or lymphoblastic lymphoma (LBL) treatment, and there is little information regarding ON in Korean paediatric and young adult patients. This retrospective cohort study assessed the cumulative incidence of and risk factors for ON using national health insurance claims data from 2008 to 2019 in 4861 ALL/LBL patients. The Kaplan&ndash;Meier method was used to estimate the cumulative incidence of ON according to age groups; the Cox proportional hazard regression model was used to identify risk factors related to ON development after diagnosing ALL/LBL. A cause-specific hazard model with time-varying covariates was used to assess the effects of risk factors. Overall, 158 (3.25%) patients were diagnosed with ON, among whom 23 underwent orthopaedic surgeries. Older age, radiotherapy (HR = 2.62, 95% confidence interval (CI) 1.87&ndash;3.66), HSCT (HR = 2.40, 95% CI 1.74&ndash;3.31), steroid use and anthracycline use (HR = 2.76, CI 1.85&ndash;4.14) were related to ON in the univariate analysis. In the multivariate analysis, age and steroid and asparaginase use (HR = 1.99, CI 1.30&ndash;3.06) were factors associated with ON. These results suggest that Korean patients with ALL/LBL who used steroids and asparaginase should be closely monitored during follow-up, even among young adult patients