Seafarer training and rural development in China: a survey report

So far, most studies of the relationship between migration and development in rural China pay attention to rural-urban migration. As a consequence, less is known about international labour migration and access to it by sending communities. This phenomenon has two aspects: international chain migration via social networks, which happen mainly along coastal areas; and international contract labour migration from the poor areas of inland China. The research reported in this article examines the latter, exploring how the rural poor gain access to opportunities, what they cost and what their perceived benefits are

Optimizing Methanol Blending Performance of Electronically Controlled Diesel Engines through Fuzzy Analysis

This paper presents a comprehensive optimization approach for enhancing the performance of a methanol/diesel Exhaust Gas Recirculation (EGR) engine. Initially, a hybrid fuel engine combustion chamber model was developed using AVL-FIRE software, and the simulated results were compared with the values obtained from bench tests. An orthogonal experimental design was employed to optimize five key factors, namely methanol blending ratio, EGR rate, injection advance angle, intake pressure, and intake temperature. Evaluation indexes were established, with indicated power and NO emissions assigned weights of 0.35 and 0.65, respectively. The optimal parameter combinations were determined as follows: methanol blending ratio (a1=20%), EGR rate (a2=12.5%), injection advance angle (a3=16.6°CA), intake temperature (a4 = 315.15 K), and intake pressure (a5=0.173 MPa). The indicated power of the optimized configuration reached 47.8 kW, slightly lower than the original 55 kW, while the NO emission mass fraction decreased to 1.9×10-4%, representing a significant reduction of 77.6% compared to the original value of 8.5×10-4%. This optimization methodology demonstrates the effective reduction of NO emissions without compromising power performance in methanol/diesel EGR engines

Effect of Injection Advance Angle on the Performance of Butanol-Diesel Dual-fuel Engines

In order to further investigate the performance of the butanol-diesel dual-fuel engine, this paper uses the 4190ZLC-2 marine medium-speed diesel engine as a prototype and establishes a dual-fuel engine high-pressure cycle model using AVL-FIRE simulation software. The injection advance angle was set to 16.6°, 18.6°, 20.6° and 22.6° respectively, and its effect on the performance of the dual-fuel engine was investigated by varying the injection advance angle. The results show that as the injection advance angle increases, the incylinder pressure and temperature also increase. When the injection advance angle is 22.6°CA, compared with the original engine, CO emission is reduced by 16.8%, NO emission is increased by 7.4%, carbon smoke emission is reduced by 16.9%, and the indicated power is 52.6kW, which is increased by 1.8%

K⁺ and Na⁺ fluxes in roots of two Chinese Iris populations

Maintenance of ion homeostasis, particularly the regulation of K+ and Na+ uptake, is important for all plants to adapt to salinity. Observations on ionic response to salinity and net fluxes of K+, Na+ in the root exhibited by plants during salt stress have highlighted the need for further investigation. The objectives of this study were to compare salt adaptation of two Chinese Iris (Iris lactea Pall. var. chinensis (Fisch.) Koidz.) populations, and to improve understanding of adaptation to salinity exhibited by plants. Plants used in this study were grown from seeds collected in the Xinjiang Uygur Autonomous Region (Xj) and Beijing Municipality (Bj), China. Hydroponically-grown seedlings of the two populations were supplied with nutrient solutions containing 0.1 (control) and 140 mmol·L-1 NaCl. After 12 days, plants were harvested for determination of relative growth rate and K+, Na+ concentrations. Net fluxes of K+, Na+ from the apex and along the root axis to 10.8 mm were measured using non-invasive micro-test technique. With 140 mmol·L-1 NaCl treatment, shoots for population Xj had larger relative growth rate and higher K+ concentration than shoots for population Bj. However, the Na+ concentrations in both shoots and roots were lower for Xj than those for Bj. There was a lower net efflux of K+ found in population Xj than by Bj in the mature zone (approximately 2.4-10.8 mm from root tip). However, no difference in the efflux of Na+ between the populations was obtained. Population Xj of I. lactea continued to grow normally under NaCl stress, and maintained a higher K+/Na+ ratio in the shoots. These traits, which were associated with lower K+ leakage, help population Xj adapt to saline environments

K⁺ and Na⁺ fluxes in roots of two Chinese Iris populations

Maintenance of ion homeostasis, particularly the regulation of K⁺ and Na⁺ uptake, is important for all plants to adapt to salinity. Observations on ionic response to salinity and net fluxes of K⁺, Na⁺ in the root exhibited by plants during salt stress have highlighted the need for further investigation. The objectives of this study were to compare salt adaptation of two Chinese Iris (Iris lactea Pall. var. chinensis (Fisch.) Koidz.) populations, and to improve understanding of adaptation to salinity exhibited by plants. Plants used in this study were grown from seeds collected in the Xinjiang Uygur Autonomous Region (Xj) and Beijing Municipality (Bj), China. Hydroponically-grown seedlings of the two populations were supplied with nutrient solutions containing 0.1 (control) and 140 mmol·L^-1 NaCl. After 12 days, plants were harvested for determination of relative growth rate and K⁺, Na⁺ concentrations. Net fluxes of K⁺, Na⁺ from the apex and along the root axis to 10.8 mm were measured using non-invasive micro-test technique. With 140 mmol·L^-1 NaCl treatment, shoots for population Xj had larger relative growth rate and higher K⁺ concentration than shoots for population Bj. However, the Na⁺ concentrations in both shoots and roots were lower for Xj than those for Bj. There was a lower net efflux of K⁺ found in population Xj than by Bj in the mature zone (approximately 2.4-10.8 mm from root tip). However, no difference in the efflux of Na⁺ between the populations was obtained. Population Xj of I. lactea continued to grow normally under NaCl stress, and maintained a higher K⁺/Na⁺ ratio in the shoots. These traits, which were associated with lower K⁺ leakage, help population Xj adapt to saline environments

Increasing Oxygen Mass Fraction in Blind Headings of a Plateau Metal Mine by Oxygen Supply Duct Design: A CFD Modelling Approach

Hypoxia problem has always been a difficult point in plateau tunneling projects. To solve this problem, a blind heading face in a plateau metal mine in western China was taken as the physical model, and the computational fluid dynamics was used to analyze the oxygen mass fraction distribution and oxygen-increasing effect in 1 m, 3 m, and 5 m roadway sections from the heading face. The optimal ventilation system was first built to obtain the optimum height and length of the airflow ducts. Then different cases with various oxygen supply duct designs were built in 2 scenarios. The results found that different oxygen supply duct design has significant influence on the oxygen distribution in the heading face. Also, each design has different optimal height of oxygen outlet. The oxygen supply effect is best when some small holes are made in the oxygen supply duct to diffuse oxygen to the working surface. The finding of this paper is helpful for effective and economical oxygen supply in roadway excavation of plateau metal mine and tunnel

Optimizing Methanol Blending Performance of Electronically Controlled Diesel Engines through Fuzzy Analysis

This paper presents a comprehensive optimization approach for enhancing the performance of a methanol/diesel Exhaust Gas Recirculation (EGR) engine. Initially, a hybrid fuel engine combustion chamber model was developed using AVL-FIRE software, and the simulated results were compared with the values obtained from bench tests. An orthogonal experimental design was employed to optimize five key factors, namely methanol blending ratio, EGR rate, injection advance angle, intake pressure, and intake temperature. Evaluation indexes were established, with indicated power and NO emissions assigned weights of 0.35 and 0.65, respectively. The optimal parameter combinations were determined as follows: methanol blending ratio (a1=20%), EGR rate (a2=12.5%), injection advance angle (a3=16.6°CA), intake temperature (a4 = 315.15 K), and intake pressure (a5=0.173 MPa). The indicated power of the optimized configuration reached 47.8 kW, slightly lower than the original 55 kW, while the NO emission mass fraction decreased to 1.9×10-4%, representing a significant reduction of 77.6% compared to the original value of 8.5×10-4%. This optimization methodology demonstrates the effective reduction of NO emissions without compromising power performance in methanol/diesel EGR engines

Effect of Injection Advance Angle on the Performance of Butanol-Diesel Dual-fuel Engines

In order to further investigate the performance of the butanol-diesel dual-fuel engine, this paper uses the 4190ZLC-2 marine medium-speed diesel engine as a prototype and establishes a dual-fuel engine high-pressure cycle model using AVL-FIRE simulation software. The injection advance angle was set to 16.6°, 18.6°, 20.6° and 22.6° respectively, and its effect on the performance of the dual-fuel engine was investigated by varying the injection advance angle. The results show that as the injection advance angle increases, the incylinder pressure and temperature also increase. When the injection advance angle is 22.6°CA, compared with the original engine, CO emission is reduced by 16.8%, NO emission is increased by 7.4%, carbon smoke emission is reduced by 16.9%, and the indicated power is 52.6kW, which is increased by 1.8%