1,500 research outputs found

    Investigate the effect of EGR stratergies on the HCCI engine's performance with N-heptane fuel injection

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    In this study, the effect of EGR strategies on the HCCI engine's performance is studied. A program was established to control the injection fuel and amount of exhaust gas recirculation on the HCCI engine. The results of the research show that when the EGR rate is greater than 30%, the engine operates stably according to the HCCI combustion characteristic at speeds lower than 2400 rpm. But when engine speeds are higher than 2400 rpm, the HCCI combustion characteristic is unstable; the torque and the indicator efficiency decrease rapidly. When the HCCI engine increases the EGR rate, the start of combustion is gradually later, the coefficient gradually decreases to close to the black smoke characteristic curve, the CO, HC, and CO2 emissions increase. The NOx emissions tend to increase when the EGR ratio increases from 0–25%, but the NOx decreases when the EGR rate is greater than 25%

    Current Status of Elderly Social Support Services in Elderly Care Centers in Hanoi

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    The Article aims to elaborate and analyze the current status of social support services for the elderly in general and semi-professional social work services provided in care centers in Hanoi in particular today. The centers subject to the investigation include Social Protection Center 3 Hanoi, Dien Hong Nursing Home, Bach Nien Thien Duc Elderly Care Center, and Social Protection Center 2 Hanoi. The service performance is determined based on the satisfaction of the needs of the elderly group. The results evidence that from the point of view of the elderly, “the need for medical care, examination and treatment is the highest among other needs of the elderly (with 149 votes, taking up 64.2%), from the point of view of social support workers, the need for “someone to share their feelings” is the highest (with 144 votes, taking up 77.4%). The services subject to assessment and review to the extent of the Article include (1) Consultancy; (2) Legal aid; (3) Supporting the elderly in the integration; (4) Communication. The frequency of rendered services changes at the “sometimes received by the elderly” level, approx. 50% on average. The level of performance as assessed by the elderly and social workers is at a medium and quite high level, ranging from 2.26 to 3.30 and from 1.98 (high) to 3.1 (medium), respectively.  Keywords: the elderly, social support services, care centers DOI: 10.7176/RHSS/12-20-04 Publication date:October 31st 202

    TURBIDITY REMOVAL BY MUCILAGE FROM BASELLA ALBA

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    Coagulation and flocculation are preliminary used in water treatment processes for turbidity removal, using popularily synthetic chemicals with health and environmental concerns. The use of natural flocculants has known to be a promising alteratives for chemical ones due to their environmental friendly behavior. This research investigated turbidity removal efficiency of mucilage extracted from Basella alba - an indigenous species in Vietnam - in the role of a flocculant. The removal efficiency of mucilage was investigated in combination with PAC or Alum on To Lich river water by mean of Jar tests. PAC or Alum alone can remove maximum 97% and 90% turbidity of To Lich river water at its original pH for the sedimentation time of 30 minutes. The combination of mucilage and PAC or Alum increased the efficiencies of turbidity removal and reduced the amount of chemicals needed. The corresponding increases were maximum 7% and 18%, respectively; while the reduction of PAC/Alum used was 75-80%

    The Improvement Model of Navigational Safety for Inland Waterway Transport

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    This paper aims at evaluating navigational safety for inland waterway transport (IWT). In doing so, the literature and operational features of IWT were initially reviewed to figure out risk elements (REs) influencing the navigational safety for IWT. After that, a fuzzy Analytic Hierarchical Process (AHP) approach was adopted to estimate the weight for the likelihood and consequence measures of REs. Then, continuous risk matrix (RM) was introduced to identify REs\u27 risk level. Lastly, to test the proposed research model\u27s applicability, IWT operators across Vietnam were empirically surveyed. The empirical findings could be useful for IWT operators in launching managerial policies to boost their navigational safety. Furthermore, the proposed risk evaluation framework may serve as a methodological reference in relevant literature

    Role of GmNAC019 transcription factor in salinity and drought tolerance of transgenic Arabidopsis thaliana

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    Increasingly severe drought and salinity stress due to global climate change have made these stresses bigger threats to ecosystem and agriculture. Previous studies reported that GmNAC019, a soybean NAC transcription factor - encoding gene, displayed induced expression upon drought treatment in wild-type cultivars. In this study, drought and salinity stresses were applied on GmNAC019-overexpressing Arabidopsis plants to verify the contribution of GmNAC019 in regulating plant response to the stress conditions. Results from the water loss rate and survival rate assays revealed that the transgenic line conferred improved tolerance to drought stress as evidenced by lower leaf water loss and significantly higher rate of survival than seen in the wild-type plants. Similarly, the survival rate assay for testing salinity effects on plants by growing the plants on MS medium supplemented with different NaCl concentrations also indicated that the transgenic plants had a better tolerance to salt stress as they displayed lower rate of root growth inhibition and higher survival rate. Taken these results altogether, it is suggested that GmNAC019 might play important role in aiding plant response to drought and salinity stresses. Specific functions of this gene should be elaborated in future studies to evaluate its potential application for crop improvement

    Resistance of aerosolized bacterial viruses to four germicidal products

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    Viral diseases can spread through a variety of routes including aerosols. Yet, limited data are available on the efficacy of aerosolized chemicals to reduce viral loads in the air. Bacteriophages (phages) are often used as surrogates for hazardous viruses in aerosol studies because they are inexpensive, easy to handle, and safe for laboratory workers. Moreover, several of these bacterial viruses display physical characteristics similar to pathogenic human and animal viruses, like morphological size, type of nucleic acids, capsid morphology, and the presence of an envelope. In this study, the efficacy of four chemicals was evaluated on four airborne phages at two different relative humidity levels. Non-tailed bacteriophages MS2 (single-stranded RNA), ϕ6 (double-stranded RNA, enveloped), PR772 (double-stranded DNA), and ϕX174 (single-stranded DNA) were first aerosolized in a 55L rotative environmental chamber at 19°C with 25% and 50% relative humidity. Then, hydrogen peroxide, Eugenol (phenylpropene used in commercial perfumes and flavorings), Mist® (automobile disinfectant containing Triethylene glycol), and Pledge® (multisurface disinfectant containing Isopropanol, n-Alkyl Dimethyl Benzyl Amonium Chlorides, and n-Alkyl Dimethyl Ethylbenzyl Ammonium Chloride) were nebulized with the phages using a separate nebulizer. Aerosols were maintained in suspension during 10 minutes, 1 hour, and 2 hours. Viral aerosols were sampled using an SKC BioSampler and samples were analyzed using qPCR and plaque assays. The resistance levels of the four phages varied depending on the relative humidity (RH) and germicidal products tested. Phage MS2 was the most stable airborne virus under the environmental conditions tested while phage PR772 was the least stable. Pledge® and Eugenol reduced the infectivity of all airborne phages tested. At 25% RH, Pledge® and Eugenol were more effective at reducing infectivity of RNA phages ϕ6 and MS2. At 50% RH, Pledge® was the most effective agent against phage MS2. These findings illustrate that various airborne viruses should be tested to demonstrate the effectiveness of germicidal treatments. This research also provides a set of parameters for testing germicidal products in large-scale settings to reduce the risk of virus transmission

    Elastic and thermodynamic properties of the major clinker phases of Portland cement: Insights from first principles calculations

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    Portland based cement is one of the most popular materials used in the civil and construction applications. Reliable computational methods to provide an insight into the underlying mechanics of the major phases of this material are of great interest for cement design. The present work investigated the performance of density functional theory (DFT) calculations using the PBE-D2 method to predict the mechanical, thermodynamic properties of four major phases namely Alite C3S, Belite C2S, tricalcium aluminate C3A and tetracalcium aluminoferrite C4AF. The calculated elastic properties were in a good agreement with available experimental data. In addition, a deeper insight into the electron density of state, spin-polarization, atomic charge, as well as free energy and entropy properties were also presented. Further development is necessary to improve the established DFT models for predicting the mechanical properties of the ferrite phase of Portland clinker.publishedVersio

    The role of tradition for food and wine producing firms in times of an unprecedented crisis

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    Purpose: The purpose of the present study is twofold. First, the study will investigate the importance of tradition for businesses operating during the COVID-19 crisis, notably, as a valuable proposition and strategy. Second, the study seeks to advance theoretical understanding, proposing two frameworks based upon emerging dimensions, the resource-based view and dynamic capabilities. Design/methodology/approach: An online survey gathered the views of 107 predominantly micro and small-scale owner-manager and family-owned firms involved in the food and wine sector. These participants are based in Italy, one of the hardest-hit countries in the crisis. Findings: Three fundamental dimensions emerge from the findings. The first, “embedded advantage”, concerns firms’ more direct involvement and tradition-related actions. The second, “active advantage”, highlights the already established value of tradition, for example, through firm identity gained, well-established roots and firm culture. The third dimension, “strategic fusion”, underscores the importance of upgrading the business model, where innovation complements tradition strategically. Originality/value: The study’s revealed dimensions provide new conceptual perspectives to understand tradition in the context of firms confronting an unprecedented event. The first proposed theoretical framework illustrates that firms appear to mainly rely on tradition as the fundamental pillar of their overall strategy. Additionally, other firms engage in actions to consolidate tradition’s strategic significance, while others embrace innovation to further strengthen their competitiveness. The second framework emphasises relations between these dimensions and key attributes associated with the two adopted theoretical foundations, where the need to “reconfigure tradition” clearly emerges
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