Investigation of cylinder deactivation and variable valve actuation on gasoline engine performance

Increasingly stringent regulations on gasoline engine fuel consumption and exhaust emissions require additional technology integration such as Cylinder Deactivation (CDA) and Variable valve actuation (VVA) to improve part load engine efficiency. At part load, CDA is achieved by closing the inlet and exhaust valves and shutting off the fuel supply to a selected number of cylinders. Variable valve actuation (VVA) enables the cylinder gas exchange process to be optimised for different engine speeds by changing valve opening and closing times as well as maximum valve lift. The focus of this study was the investigation of effect of the integration of the above two technologies on the performance of a gasoline engine operating at part load conditions. In this study, a 1.6 Litre in-line 4-cylinder gasoline engine is modelled on engine simulation software and simulated data is analysed to show improvements in fuel consumption, CO2 emissions, pumping losses and effects on CO and NOx emissions. A CDA and VVA operating window is identified which yields brake specific fuel consumption improvements of 10-20% against the base engine at engine speeds between 1000rpm to 3500rpm at approximately 12.5% load. Highest concentration of CO emissions was observed at between 4 to 5 bar BMEP at 4000rpm and highest concentration of NOx at the same load range but at 1000rpm.Findings based on simulation results point towards significant part load performance improvements which can be achieved by integrating cylinder deactivation and variable valve actuation on gasoline engines. Copyright © 2014 SAE International

Information Use by PhD Students in Agriculture and Biology: A Dissertation Citation Analysis

This article reports the findings of a study conducted to examine the types of information used by graduate students in the fields of biological and agricultural sciences at Iowa State University (ISU). The citations of doctoral dissertations submitted in nine agriculture and biological science subject fields (crop production and physiology; molecular, cellular, and developmental biology; entomology; genetics; microbiology; plant breeding; plant pathology; plant physiology; and soil science) at ISU from 1997–2006 were analyzed. The article discusses the types and ages of resources cited in the different subject fields studied. The most cited journals in each discipline were identified, and the journal title dispersion was examined

RLZAP: Relative Lempel-Ziv with Adaptive Pointers

Relative Lempel-Ziv (RLZ) is a popular algorithm for compressing databases of genomes from individuals of the same species when fast random access is desired. With Kuruppu et al.'s (SPIRE 2010) original implementation, a reference genome is selected and then the other genomes are greedily parsed into phrases exactly matching substrings of the reference. Deorowicz and Grabowski (Bioinformatics, 2011) pointed out that letting each phrase end with a mismatch character usually gives better compression because many of the differences between individuals' genomes are single-nucleotide substitutions. Ferrada et al. (SPIRE 2014) then pointed out that also using relative pointers and run-length compressing them usually gives even better compression. In this paper we generalize Ferrada et al.'s idea to handle well also short insertions, deletions and multi-character substitutions. We show experimentally that our generalization achieves better compression than Ferrada et al.'s implementation with comparable random-access times

Practices Followed to Manage Plastic Waste including Shopping Bags and Lunch Sheets in Sri Lanka: A Preliminary Study in Western Province

Although plastics have made the workings of our lives easier, it has created many different environmental and social problems due to poor management practices. The problem of plastic waste has been exacerbated due to various regulations that have been introduced from time to time for the sustainable management of plastic waste. However, those are not properly implemented. The main objective of this study is to examine the best practices in Sri Lanka for the management of plastic waste, including shopping bags and lunch sheets (PBLS). Further, the study illustrated the prevailing and possible alternatives for polythene products in Sri Lanka and weaknesses in the identification of alternatives. The study was conducted in the Western Province covering three districts: Colombo, Gampaha and Kalutara. Data collection was conducted through different structured questionnaire surveys, key informant interviews and a major workshop from a sample of 1314 respondents. Results revealed that 59% of households in the survey confirm that they were discouraged from switching to alternatives as a result of freely available low-density polyethylene (LDPE) bags in the market. Also, 67% of the households and 74% of the supermarkets pointed out that, the current polythene bag usage was higher prior to the ban, due to the poor strength and quality of the bag. Further, the study reveals that ‘Extended Producer Responsibility (EPR)’ has the potential to influence material management systems and prevent pollution and has been successfully tested in many countries around the world. DOI: http://doi.org/10.31357/fhss/vjhss.v07i01.0

Filter based methods for statistical linear inverse problems

Ill-posed inverse problems are ubiquitous in applications. Understanding of algorithms for their solution has been greatly enhanced by a deep understanding of the linear inverse problem. In the applied communities ensemble-based filtering methods have recently been used to solve inverse problems by introducing an artificial dynamical system. This opens up the possibility of using a range of other filtering methods, such as 3DVAR and Kalman based methods, to solve inverse problems, again by introducing an artificial dynamical system. The aim of this paper is to analyze such methods in the context of the linear inverse problem. Statistical linear inverse problems are studied in the sense that the observational noise is assumed to be derived via realization of a Gaussian random variable. We investigate the asymptotic behavior of filter based methods for these inverse problems. Rigorous convergence rates are established for 3DVAR and for the Kalman filters, including minimax rates in some instances. Blowup of 3DVAR and a variant of its basic form is also presented, and optimality of the Kalman filter is discussed. These analyses reveal a close connection between (iterated) regularization schemes in deterministic inverse problems and filter based methods in data assimilation. Numerical experiments are presented to illustrate the theory

Approaches for Sample Characterization and Lithography with Nanoparticles using Modes of Scanning Probe Microscopy

Measurement and imaging modes of scanning probe microscopy (SPM) have been routinely applied for characterizing systems of nanoparticles; however the evolution of fabrication methods to prepare arrangements of nanoparticles remains a challenge. Reproducible fabrication of surface structures which integrate nanoparticles within ultra-small patterns will require innovative approaches to achieve high throughput and precision. Strategies for nanoscale lithography have been introduced for preparing defined arrangements of nanoparticles on surfaces based on physical or chemical interactions. For example, physisorption was employed for attaching nanoparticles based on colloidal lithography and site-directed assembly. Microfabricated atomic force microscope (AFM) tips with capillary channels have been used to pattern nanoparticles through electrostatic interactions. Specific chemical interactions can be designed for patterning nanoparticles with dip-pen nanolithography and SPM-based fabrication. Studies with nanoparticles are reviewed, which have applied either in situ and ex situ approaches for imaging and measurements using modes of SPM. The imaging principle for contact and tapping modes are described with example studies of nanoparticle patterns. The SPM modes for measuring physical properties (e.g. magnetism, softness, conductance) using force modulation microscopy (FMM), magnetic force microscopy (MFM), magnetic sample modulation (MSM), and conductive probe AFM are described for selected studies of lithography with nanoparticles. Strategies for patterning nanoparticles using lithography modes of nanoshaving, dip-pen nanolithography, and tip-induced oxidation have been reported for a range of nanoparticle systems. Applications for nanotechnology will require the integration of nanoparticles within engineered surface architectures. Stable, organized arrangements of nanoparticles with robust chemical/physical attachment to surfaces will be needed for applications, to fully gain advantages of the characteristic quantum properties of nanoparticles

Relative Lempel-Ziv Compression of Suffix Arrays

We show that a combination of differential encoding, random sampling, and relative Lempel-Ziv (RLZ) parsing is effective for compressing suffix arrays, while simultaneously allowing very fast decompression of arbitrary suffix array intervals, facilitating pattern matching. The resulting text index, while somewhat larger (5-10x) than the recent r-index of Gagie, Navarro, and Prezza (Proc. SODA ’18)—still provides significant compression, and allows pattern location queries to be answered more than two orders of magnitude faster in practice.Peer reviewe

Estimation of Fracture Toughness of Anisotropic Rocks by Semi-Circular Bend (SCB) Tests Under Water Vapor Pressure

In order to investigate the influence of water vapor pressure in the surrounding environment on mode I fracture toughness (KIc) of rocks, semi-circular bend (SCB) tests under various water vapor pressures were conducted. Water vapor is one of the most effective agents which promote stress corrosion of rocks. The range of water vapor pressure used was 10−2 to 103 Pa, and two anisotropic rock types, African granodiorite and Korean granite, were used in this work. The measurement of elastic wave velocity and observation of thin sections of these rocks were performed to investigate the microstructures of the rocks. It was found that the distribution of inherent microcracks and grains have a preferred orientation. Two types of specimens in different orientations, namely Type-1 and Type-3, were prepared based on the anisotropy identified by the differences in the elastic wave velocity. KIc of both rock types was dependent on the water vapor pressure in the surrounding environment and decreased with increasing water vapor pressure. It was found that the degree of the dependence is influenced by the orientation and density of inherent microcracks. The experimental results also showed that KIc depended on the material anisotropy. A fracture process was discussed on the basis of the geometry of fractures within fractured specimens visualized by the X-ray computed tomography (CT) method. It was concluded that the dominant factor causing the anisotropy of KIc is the distribution of grains rather than inherent microcracks in these rocks

The Evolution of Fangs, Venom, and Mimicry Systems in Blenny Fishes

Venom systems have evolved on multiple occasions across the animal kingdom, and they can act as key adaptations to protect animals from predators. Consequently, venomous animals serve as models for a rich source of mimicry types, as non-venomous species benefit from reductions in predation risk by mimicking the coloration, body shape, and/or movement of toxic counterparts. The frequent evolution of such deceitful imitations provides notable examples of phenotypic convergence and are often invoked as classic exemplars of evolution by natural selection. Here, we investigate the evolution of fangs, venom, and mimetic relationships in reef fishes from the tribe Nemophini (fangblennies). Comparative morphological analyses reveal that enlarged canine teeth (fangs) originated at the base of the Nemophini radiation and have enabled a micropredatory feeding strategy in non-venomous Plagiotremus spp. Subsequently, the evolution of deep anterior grooves and their coupling to venom secretory tissue provide Meiacanthus spp. with toxic venom that they effectively employ for defense. We find that fangblenny venom contains a number of toxic components that have been independently recruited into other animal venoms, some of which cause toxicity via interactions with opioid receptors, and result in a multifunctional biochemical phenotype that exerts potent hypotensive effects. The evolution of fangblenny venom has seemingly led to phenotypic convergence via the formation of a diverse array of mimetic relationships that provide protective (Batesian mimicry) and predatory (aggressive mimicry) benefits to other fishes. Our results further our understanding of how novel morphological and biochemical adaptations stimulate ecological interactions in the natural world