Injection Parameters Effect on the Performance of Compressed Natural Gas Direct Injection (CNG-DI) Engine Under Lean Stratified Conditions

Natural gas has been identified as an alternative to crude oil fuels such as gasoline and diesel. Natural gas utilization as an automotive fuel is yet to be fully used to its optimum because most of the vehicles converted to natural gas are still using port injection or carburetors. Natural gas can be used either in compressed (CNG) or liquefied (LNG) fom1. Compressed natural gas (CNG) has huge potential for improving the them1al efficiency of spark ignited (SI) engines due to combustion-specific properties such as high knock resistance and extreme stratification capabilities for lean air/fuel ratio. The main drawback or disadvantage of using natural gas in the engine is that its perfom1ance drops compared to gasoline or diesel engine. For current passenger car standard applications a power drop of approximately I 0% is noticed by use of CNG. The prime source of perfom1ance drop is because of lower volumetric efficiency, lower energy density and longer combustion duration of natural gas. Reduced volumetric efficiency of induction system is being widely studied to optimize for the losses causing this diminution. This drawback can be compensated by direct injection of CNG straight into the combustion chamber, and therefore giving way to utilize the maximum benefits from using CNG as automotive fuel. Combustion of natural gas is cleaner i.e. lower exhaust emissions, also because of its higher octane number, the engines can be designed with higher compression ratios, hence increasing the them1al efficiency. Direct injection systems for natural gas engme are expected to solve the problem of lower volumetric efficiency. Optimization of injection parameters is required for the optimum outcome of natural gas engine. Besides favorable engine out emissions, the engine concept operates without power loss and with absolute low fuel consumption. The "Direct CNG Injection" may be a highly attractive solution for automotive propulsion systems. The following research is carried out on a dedicated 4-stroke natural gas spark ignition engine with a compression ratio of 14. A centre direct injection system is used, where the injector is placed at the centre of cylinder head with spark plug offset by 6mm. Engine is being tested for idle and partload conditions using homogeneous and stratified pistons. Injection parameters such as injection timing and injector spray angle are investigated while keeping the injection pressure constant, to find out the effect of injection parameters on CNG-01 engine. Ignition timing is adjusted to obtain the maximum brake torque (MBT). Results for both stoichiometric and stratified charges at idle and partload conditions are compared to examine the features of both operations under these conditions. The experimental results are categorized based on each injection parameter. Firstly, injection timing from early injection (300 degree BTDC) to late injection (80 degree BTDC) is investigated for stoichiometric conditions. For stratified operation the injection starts after the closing of air intake valve at 132 BTDC. The injection is delayed further till the limit for each RPM as set by the ECU (Engine Control Unit). Injection timing effect for idle and partloads is compared for stoichiometric and lean stratified operations, for injection timings starting after the closing of intake valve. Engine speed is limited from 2000 to 5000 RPM. Injection pressure is kept constant at 18 bars for both stoichiometric and stratified operations. Injection pressure is affecting the fuel delivery rate. Lower injection pressure needs longer injection duration to deliver the required fuel to the engine. Two injectors with different injection angle are investigated, 30 deg (NAI) and 70 deg (W AI). Both injectors have their distinctive characteristics which can be applied on certain engine operational conditions. Lean stratified operation proved to be better for lower engine speeds while having overall lower brake specific fuel consumption over a wide range. Lower performance at higher engine speeds is due to less time for mixture formation, lower fuel content and excessive stratification. Wide angle injector (W AI) proves to be giving better performance than narrow angle injector (NAI) at lean conditions. Faster mixing rate of W AI might be responsible for such behavior. Nitrogen oxides (NOx) emission for lean stratified operation is higher at lower engine speeds which indicate higher temperatures of combustion, for all injection timings except the lean limit where it is lesser. Unburned hydrocarbons are slightly higher than stoichiometric and tend to increase with the engine speed. Higher cycle to cycle variation, mixture fom1ation, excessive stratification and bulk quenching are the reasons for such behaviors. Carbon monoxide (CO) emissions for lean strati tied operation are quite lower compared to stoichiometric for all injection timings

Injection Parameters Effect on the Perfom1ance of Compressed Natural Gas Direct Injection (CNG-DI) Engine under Lean Stratified Conditions

Natural gas has been identified as an alternative to crude oil fuels such as gasoline and diesel. Natural gas utilization as an automotive fuel is yet to be fully used to its optimum because most of the vehicles converted to natural gas are still using port injection or carburetors. Natural gas can be used either in compressed (CNG) or liquefied (LNG) fom1. Compressed natural gas (CNG) has huge potential for improving the them1al efficiency of spark ignited (SI) engines due to combustion-specific properties such as high knock resistance and extreme stratification capabilities for lean air/fuel ratio. The main drawback or disadvantage of using natural gas in the engine is that its perfom1ance drops compared to gasoline or diesel engine. For current passenger car standard applications a power drop of approximately I 0% is noticed by use of CNG. The prime source of perfom1ance drop is because of lower volumetric efficiency, lower energy density and longer combustion duration of natural gas. Reduced volumetric efficiency of induction system is being widely studied to optimize for the losses causing this diminution. This drawback can be compensated by direct injection of CNG straight into the combustion chamber, and therefore giving way to utilize the maximum benefits from using CNG as automotive fuel. Combustion of natural gas is cleaner i.e. lower exhaust emissions, also because of its higher octane number, the engines can be designed with higher compression ratios, hence increasing the them1al efficiency. Direct injection systems for natural gas engme are expected to solve the problem of lower volumetric efficiency. Optimization of injection parameters is required for the optimum outcome of natural gas engine. Besides favorable engine out emissions, the engine concept operates without power loss and with absolute low fuel consumption. The "Direct CNG Injection" may be a highly attractive solution for automotive propulsion systems. The following research is carried out on a dedicated 4-stroke natural gas spark ignition engine with a compression ratio of 14. A centre direct injection system is used, where the injector is placed at the centre of cylinder head with spark plug offset by 6mm. Engine is being tested for idle and partload conditions using homogeneous and stratified pistons. Injection parameters such as injection timing and injector spray angle are investigated while keeping the injection pressure constant, to find out the effect of injection parameters on CNG-01 engine. Ignition timing is adjusted to obtain the maximum brake torque (MBT). Results for both stoichiometric and stratified charges at idle and partload conditions are compared to examine the features of both operations under these conditions. The experimental results are categorized based on each injection parameter. Firstly, injection timing from early injection (300 degree BTDC) to late injection (80 degree BTDC) is investigated for stoichiometric conditions. For stratified operation the injection starts after the closing of air intake valve at 132 BTDC. The injection is delayed further till the limit for each RPM as set by the ECU (Engine Control Unit). Injection timing effect for idle and partloads is compared for stoichiometric and lean stratified operations, for injection timings starting after the closing of intake valve. Engine speed is limited from 2000 to 5000 RPM. Injection pressure is kept constant at 18 bars for both stoichiometric and stratified operations. Injection pressure is affecting the fuel delivery rate. Lower injection pressure needs longer injection duration to deliver the required fuel to the engine. Two injectors with different injection angle are investigated, 30 deg (NAI) and 70 deg (W AI). Both injectors have their distinctive characteristics which can be applied on certain engine operational conditions. Lean stratified operation proved to be better for lower engine speeds while having overall lower brake specific fuel consumption over a wide range. Lower performance at higher engine speeds is due to less time for mixture formation, lower fuel content and excessive stratification. Wide angle injector (W AI) proves to be giving better performance than narrow angle injector (NAI) at lean conditions. Faster mixing rate of W AI might be responsible for such behavior. Nitrogen oxides (NOx) emission for lean stratified operation is higher at lower engine speeds which indicate higher temperatures of combustion, for all injection timings except the lean limit where it is lesser. Unburned hydrocarbons are slightly higher than stoichiometric and tend to increase with the engine speed. Higher cycle to cycle variation, mixture fom1ation, excessive stratification and bulk quenching are the reasons for such behaviors. Carbon monoxide (CO) emissions for lean strati tied operation are quite lower compared to stoichiometric for all injection timings

Tibial plateau fractures: A new classification scheme

Fractures of the tibial plateaus are common injuries. Various classification schemes have been used to describe these injuries. Although each system has its own purpose, the simpler systems do not allow comparison with more complex divisions. The problem is compounded by the variable use of adjectives that describe these fractures. A comprehensive classification of tibial plateau fractures should group fractures that are similar in topography, morphology, and pathogenesis, requiring similar treatment, and having a similar prognosis. Fracture dislocations and standard tibial plateau fractures should be incorporated into a single classification to avoid the use of two complementary classifications. Any such classification should not be difficult to remember or to use. Keeping in mind these requirements, the authors devised a simple yet comprehensive classification. The authors studied 80 cases of tibial plateau fractures from January 1988 to September 1997, and used contemporary classifications of tibial plateau fractures as a database to formulate the new classification. A new fracture, subcondylar bicondylar with coronal split, has been classified for the first time. An alphanumeric system has been developed that has made nomenclature easy to remember and use. An effort has been made to address the profoundly confusing issue of variable adjectives that describe these injuries. A review of the literature shows that fractures in the authors\u27 classification have been grouped according to similar pathomechanics, treatment, and functional results

Community Based Assessment of Behavior and Awareness of Risk Factors of Cystic Echinococcosis in Major Cities of Pakistan: A One Health Perspective.

Background: The parasitic disease, cystic echinococcosis (CE), is a serious health problem in Pakistan. Risk of disease transmission is increased by economic and political instability, poor living conditions, and limited awareness of hygienic practices. The current study aimed to investigate the community perception and awareness regarding the risk factors of CE in Pakistan, from a One Health perspective. Methods: We conducted a community-based survey involving 454 participants in the major cities of Pakistan. Quantitative data based on knowledge, attitude, and practices (KAP), the One Health concept, risk factors, and community perception of CE among the general population of the major cities of Pakistan were collected. The questions included those related to knowledge, attitude, practices, One Health concept, risk factors, and community perception. The Chi-squared test was applied to determine the associations regarding KAPs across socio-demographic parameters. Results: KAPs had no significant associations with sociodemographic aspects such as age, sex, religion, ethnicity, education, marital status, occupation, or financial status of the participants. The findings indicated a lack of awareness about CE among the participants. Respondents were unaware of the risk factors and the One Health concept of CE. However, the community attitude and perception were positive toward the control of CE. Conclusion: Illiteracy, deficient sanitation systems and lack of awareness are the contributing factors to CE in Pakistan. It is necessary to make the community aware regarding CE and its importance. Increasing this awareness represents an important step toward the eradication and control of CE

Global, regional, and national progress towards Sustainable Development Goal 3.2 for neonatal and child health: all-cause and cause-specific mortality findings from the Global Burden of Disease Study 2019

Background Sustainable Development Goal 3.2 has targeted elimination of preventable child mortality, reduction of neonatal death to less than 12 per 1000 livebirths, and reduction of death of children younger than 5 years to less than 25 per 1000 livebirths, for each country by 2030. To understand current rates, recent trends, and potential trajectories of child mortality for the next decade, we present the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 findings for all-cause mortality and cause-specific mortality in children younger than 5 years of age, with multiple scenarios for child mortality in 2030 that include the consideration of potential effects of COVID-19, and a novel framework for quantifying optimal child survival. Methods We completed all-cause mortality and cause-specific mortality analyses from 204 countries and territories for detailed age groups separately, with aggregated mortality probabilities per 1000 livebirths computed for neonatal mortality rate (NMR) and under-5 mortality rate (USMR). Scenarios for 2030 represent different potential trajectories, notably including potential effects of the COVID-19 pandemic and the potential impact of improvements preferentially targeting neonatal survival. Optimal child survival metrics were developed by age, sex, and cause of death across all GBD location-years. The first metric is a global optimum and is based on the lowest observed mortality, and the second is a survival potential frontier that is based on stochastic frontier analysis of observed mortality and Healthcare Access and Quality Index. Findings Global U5MR decreased from 71.2 deaths per 1000 livebirths (95% uncertainty interval WI] 68.3-74-0) in 2000 to 37.1 (33.2-41.7) in 2019 while global NMR correspondingly declined more slowly from 28.0 deaths per 1000 live births (26.8-29-5) in 2000 to 17.9 (16.3-19-8) in 2019. In 2019,136 (67%) of 204 countries had a USMR at or below the SDG 3.2 threshold and 133 (65%) had an NMR at or below the SDG 3.2 threshold, and the reference scenario suggests that by 2030,154 (75%) of all countries could meet the U5MR targets, and 139 (68%) could meet the NMR targets. Deaths of children younger than 5 years totalled 9.65 million (95% UI 9.05-10.30) in 2000 and 5.05 million (4.27-6.02) in 2019, with the neonatal fraction of these deaths increasing from 39% (3.76 million 95% UI 3.53-4.021) in 2000 to 48% (2.42 million; 2.06-2.86) in 2019. NMR and U5MR were generally higher in males than in females, although there was no statistically significant difference at the global level. Neonatal disorders remained the leading cause of death in children younger than 5 years in 2019, followed by lower respiratory infections, diarrhoeal diseases, congenital birth defects, and malaria. The global optimum analysis suggests NMR could be reduced to as low as 0.80 (95% UI 0.71-0.86) deaths per 1000 livebirths and U5MR to 1.44 (95% UI 1-27-1.58) deaths per 1000 livebirths, and in 2019, there were as many as 1.87 million (95% UI 1-35-2.58; 37% 95% UI 32-43]) of 5.05 million more deaths of children younger than 5 years than the survival potential frontier. Interpretation Global child mortality declined by almost half between 2000 and 2019, but progress remains slower in neonates and 65 (32%) of 204 countries, mostly in sub-Saharan Africa and south Asia, are not on track to meet either SDG 3.2 target by 2030. Focused improvements in perinatal and newborn care, continued and expanded delivery of essential interventions such as vaccination and infection prevention, an enhanced focus on equity, continued focus on poverty reduction and education, and investment in strengthening health systems across the development spectrum have the potential to substantially improve USMR. Given the widespread effects of COVID-19, considerable effort will be required to maintain and accelerate progress. Copyright (C) 2021 The Author(s). Published by Elsevier Ltd

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Tibial plateau fractures: A new classification scheme

Fractures of the tibial plateaus are common injuries. Various classification schemes have been used to describe these injuries. Although each system has its own purpose, the simpler systems do not allow comparison with more complex divisions. The problem is compounded by the variable use of adjectives that describe these fractures. A comprehensive classification of tibial plateau fractures should group fractures that are similar in topography, morphology, and pathogenesis, requiring similar treatment, and having a similar prognosis. Fracture dislocations and standard tibial plateau fractures should be incorporated into a single classification to avoid the use of two complementary classifications. Any such classification should not be difficult to remember or to use. Keeping in mind these requirements, the authors devised a simple yet comprehensive classification. The authors studied 80 cases of tibial plateau fractures from January 1988 to September 1997, and used contemporary classifications of tibial plateau fractures as a database to formulate the new classification. A new fracture, subcondylar bicondylar with coronal split, has been classified for the first time. An alphanumeric system has been developed that has made nomenclature easy to remember and use. An effort has been made to address the profoundly confusing issue of variable adjectives that describe these injuries. A review of the literature shows that fractures in the authors\u27 classification have been grouped according to similar pathomechanics, treatment, and functional results

Learners’ Perceptions on WhatsApp Integration as a Learning Tool to Develop EFL Spoken Vocabulary

Technology integration has a great impact on learners’ learning styles and everyday life, where various encouraging responses come across in language learning institutions through the use of mobile technology. WhatsApp application instantly transfers information in different modes. At the present time it can be effectively used as a platform to engage learners with conventional classroom setting. The present study is an attempt to investigate learners’ attitudes towards WhatsApp application and their intention for future use. 32 EFL learners were exposed to learn vocabulary by the use of WhatsApp application for a period of 6 weeks. Data were collected by using questionnaire and semi-structured interviews. The result exhibited higher levels (M= 4.4 and Mode 4.37) of the mean scores of the learners’ perception and (M= 4.3) on WhatsApp Usage attitudes. The finding of the study indicated that learners expressed positive attitudes in using WhatsApp applications for vocabulary development. The present study also suggests that the integration of WhatsApp should be fortified to learners, instructors and institutions in developing other language learning process