Variable Valve Timing Scheduling in a 4-Stroke Internal Combustion Cylinder Utilizing Artificial Neural Networks

The apparently simple structure of a four-stroke internal combustion cylinder belies the complicated problem of optimizing valve operation in response to a change in crankshaft rotation speed. The objective of this study was to determine the cylinder pressure for valve event angles in order to determine the optimal strategy for the timing of valve events when independently-actuated valves are available. In this work, an artificial neural network is applied to create a prediction matrix to anticipate the best variable valve timing approach according to rotation speed

Identification and Isolation of Mollisols in Savadkooh region

The present study was carried out in Savadkooh region, Mazandaran province, North of Iran, to evaluate and identify, what kind of soils are in this area. The study area is under landuse of forest, rice fields and city. The results showed, because of high organic matter and presence of other conditions in forest area, Mollisols were dominant soils in Savadkooh region. Although, we detected 40% Inceptisols, but the similarity of these soils to each other, we guess landuse change, is the main cause to lack of mollic epipedon and decrease in organic matter. So probabely, more than half of Inceptisols, were Mollisols and after changing in landuse, they became Inceptisols. Entisols and Alfisols had the minimun area in Savadkooh. The present study provides a general concept of presentation of Mollisols in Savadkooh region

Responses of carbon, nitrogen and phosphorus to two consecutive drying–rewetting cycles in soils

Drying and rewetting cycles are known to be important for the dynamics of carbon (C), phosphorus (P) and nitrogen (N) in soils. This study reports the short-term responses of these nutrients to consecutive drying and rewetting cycles and how varying soil moisture content affects the presence of different forms of C, P and N, microbial biomass C and P (MBC and MBP), as well as associated carbon dioxide (CO2) and nitrous oxide (N2O) emissions. Soils were incubated for 14 days during which two successive drying-rewetting episodes were imposed on the soils. Soils subjected to drying (DRW) were rewetted on the seventh day of each drying period to return them to 60% water holding capacity, whilst continually moist samples (M), with soil maintained at 60% water holding capacity, were used as control samples. During the first 7 days, the DRW samples showed significant increases in extractable ammonium, total oxidised nitrogen, and bicarbonate extractable P concentrations. Rewetting after the first drying event produced significant increases only in CO2 flux. The MBC and MBP concentrations fluctuated throughout the incubation in both treatments and only the second drying-rewetting event resulted in a significantly MBC decrease. The two drying-rewetting events impacted the microbial biomass, but distinguishing the different impacts of microbial versus physical impacts of the perturbation is difficult. Moreover, this study has shown that the interactions between the macronutrient cycles in soils under drying-rewetting events is complex and different for each nutrient. However, it might be important to understand how soils will react to changing patterns of longer period of drying-rewetting to forecast the impacts of future climate change

Authenticity: A Grand Narrative in Tourism That Is Still in Demand!

Authenticity in tourism has been a subject of debate for many years, drawing perspectives from various disciplines, including anthropology, sociology, psychology, and philosophy. While some view authenticity as an objective quality of things, events, or places, others argue that authentic experience is of little importance and the true value lies in creating memorable experiences away from home. Despite being introduced more than fifty years ago, there are still many uncertainties surrounding the nature, significance, emergence, and outcomes of authenticity in tourism. This concept holds great importance in tourism, not only from a theoretical standpoint but also in its practical applications in planning, development, and marketing. Many tourist destinations and attractions strive to position themselves as authentic to stand out in a competitive market. This paper provides a conceptual review of the evolution of authenticity in tourism and explores new directions and opportunities for future research

Investigating the Effects of Variable Valve Timing on Spark Ignition Engine Performance

ABSTRACT: In this study, a prototype four-stroke spark ignition engine with four-cylinder (that each cylinder has two valves), with and without turbocharger which equipped with a system to adjustment of variable valve duration has been investigated. This study covers the effects of intake valve opening (IVO), Intake valve closing (IVC), exhaust valve opening (EVO) and exhaust valve closing (EVC) angles on engine performances and fuel economy. The calculations of engine performance were carried out using the1-Dimensional simulation with AVL BOOST software. The effects of different valve timing strategies and a combination of them from simulations were analyzed and compared with the reference fixed valve timing cases. It has been shown that substantial improvements in fuel consumption and performance can be achieved. The improvements of Indicate Specific Fuel Consumption (ISFC) are remarkable in turbocharged models. Furthermore, we can see the noticeable improvements in torque and power in the naturally aspirated engine

Variable Valve Timing Scheduling in a 4-Stroke Internal Combustion Cylinder Utilizing Artificial Neural Networks

The apparently simple structure of a four-stroke internal combustion cylinder belies the complicated problem of optimizing valve operation in response to a change in crankshaft rotation speed. The objective of this study was to determine the cylinder pressure for valve event angles in order to determine the optimal strategy for the timing of valve events when independently-actuated valves are available. In this work, an artificial neural network is applied to create a prediction matrix to anticipate the best variable valve timing approach according to rotation speed

Drying-Rewetting Cycles Affect Fungal and Bacterial Growth Differently in an Arable Soil

Drying and rewetting is a frequent physiological stress for soil microbial communities; a stress that is predicted to grow more influential with future climate change. We investigated the effect of repeated drying-rewetting cycles on bacterial (leucine incorporation) and fungal (acetate in ergosterol incorporation) growth, on the biomass concentration and composition (PLFA), and on the soil respiration. Using different plant material amendments, we generated soils with different initial fungal:bacterial compositions that we exposed to 6-10 repetitions of a drying-rewetting cycle. Drying-rewetting decreased bacterial growth while fungal growth remained unaffected, resulting in an elevated fungal:bacterial growth ratio. This effect was found irrespective of the initial fungal:bacterial biomass ratio. Many drying-rewetting cycles did not, however, affect the fungal:bacterial growth ratio compared to few cycles. The biomass response of the microbial community differed from the growth response, with fungal and total biomass only being slightly negatively affected by the repeated drying-rewetting. The discrepancy between growth- and biomass-based assessments underscores that microbial responses to perturbations might previously have been misrepresented with biomass-based assessments. In light of this, many aspects of environmental microbial ecology may need to be revisited with attention to what measure of the microbial community is relevant to study

Comparing and Ranking tourism websites performance based on e-satisfaction, e-trust, e-quality, and e-loyalty: A combined approach of structural equation modeling, fuzzy and analytical hierarchical process

This research aims to rank the relative performance of tourism websites in terms of e-satisfaction, e-trust, e-quality, and e-loyalty variables. To this end, two major Iranian travel websites providing accommodation (Iran Hotel Online) and tour packages (Marcopolo Corporation) were chosen and their performances were evaluated based on the four above variables. This research comprises two independent surveys. The first survey administered to a sample of 155 university professors and website designers examined the relative weights of the study variables in explaining the e-performance of these websites through structural equation modeling (SEM). The results indicate that e-quality, e-loyalty, e-trust, and e-satisfaction have the strongest impact on the e-performance, respectively. The second survey examined relative weights of the e-performance based on the websites’ existing e-customers (two categories of 154 and 187 samples) and also qualitative content analysis of the websites’ characteristics using fuzzy analytical hierarchical process (AHP). The findings served to inform that Marcopolo website obtained stronger weights for all four variables, compared with Iran Hotel Online, indicating its higher performance in all variables. At the end, the weight values from the SEM and AHP surveys were synthesized (0.580 and 0.418 for Marcopolo and Iran Hotel Online, respectively) in order to rank the websites based on their e-performances. According to the findings, Marcopolo website outperforms its counterpart in all four variables. The current paper contributes to the literature by yielding some insights into how to benchmark websites in order to improve their e-performance based on perspectives of both customers and experts