Comparison study of U+L and Y+L working face ventilation patterns on gas control in a highly gassy mine

A mine ventilation system is an important component of an underground mining system. We all know that the ventilation system design plays an important role in highly gassy mines, and the ventilation pattern is the primary factor in gob gas control in fully mechanized working faces. Because the gas emission rate is notably large in highly gassy fully mechanized working faces and the U ventilation pattern seriously restricts normal production, a new ventilation pattern is required. This paper uses a gas flow distribution numerical simulation method to analyze the gas controlling effect of U+L and Y+L patterns. The results indicate that the gas concentration of the U+L ventilation pattern is lower than that of Y+L pattern in a fully mechanized working face and its upper corner. Furthermore, the main ventilation factors that affect the gas drainage of U+L ventilation pattern are optimized through the orthogonal test and fuzzy evaluation method; it effectively reduces the gas concentration of the upper corner and the return airway. After the implementation of the optimal solution of the U+L ventilation pattern in No. 32212(1) working face of Rujigou coal mine of Ningxia Hui Autonomous Region in China, the gas concentration of the upper corner was reduced to 0,6 %, which can ensure the normal production of the coal mine

Genetically engineered pre-microRNA-34a prodrug suppresses orthotopic osteosarcoma xenograft tumor growth via the induction of apoptosis and cell cycle arrest.

Osteosarcoma (OS) is the most common primary malignant bone tumor in children, and microRNA-34a (miR-34a) replacement therapy represents a new treatment strategy. This study was to define the effectiveness and safety profiles of a novel bioengineered miR-34a prodrug in orthotopic OS xenograft tumor mouse model. Highly purified pre-miR-34a prodrug significantly inhibited the proliferation of human 143B and MG-63 cells in a dose dependent manner and to much greater degrees than controls, which was attributed to induction of apoptosis and G2 cell cycle arrest. Inhibition of OS cell growth and invasion were associated with release of high levels of mature miR-34a from pre-miR-34a prodrug and consequently reduction of protein levels of many miR-34a target genes including SIRT1, BCL2, c-MET, and CDK6. Furthermore, intravenous administration of in vivo-jetPEI formulated miR-34a prodrug significantly reduced OS tumor growth in orthotopic xenograft mouse models. In addition, mouse blood chemistry profiles indicated that therapeutic doses of bioengineered miR-34a prodrug were well tolerated in these animals. The results demonstrated that bioengineered miR-34a prodrug was effective to control OS tumor growth which involved the induction of apoptosis and cell cycle arrest, supporting the development of bioengineered RNAs as a novel class of large molecule therapeutic agents

Analysis of nonlinear suspension power harvest potential

Because the power consumption of a controlled suspension is huge, the power harvest potential of a nonlinear controlled suspension is analyzed. Instead of simplifying the suspension to a linear model or adopting some control strategies to solve the problem, this paper investigates the effect of the nonlinear characteristics on the power harvesting potential. A mathematic model is introduced to calculate the nonlinear vibration, and the amount of harvested power was obtained using the multi-scale method. A numerical validation is carried out at the end of this study. The results show that the investigated mechanical parameters affect both the vibration amplitude and the induced current, while the electric parameters only affect the induced current. The power harvesting potential of the nonlinear suspension is generally greater than the linear suspension because the frequency band of the actual pavement also contains bandwidth surrounding the body resonance point. The only exception occurs if the vehicle travels on a road with a particular profile, e.g. a sine curve. To optimize harvested power, it is better to consider the nonlinear characteristics rather than simplifying the suspension to a linear model

A PD Law Based Fuzzy Logic Control Strategy For Simultaneous Control Of Indoor Temperature And Humidity Using A Variable Speed Direct Expansion Air Conditioner

In small to medium scale buildings located in the subtropics, such as Hong Kong, direct expansion air conditioning (DX A/C) systems are widely applied. This is because, as compared to chilled water based central air conditioning systems, DX A/C systems are compact, flexible for multi-room services, energy efficient and cost less to maintain and operate. However, traditionally, a DX A/C system is equipped with a single-speed compressor and supply air fan, and employs ON / OFF control strategy to maintain indoor air temperature only, leaving the indoor moisture content (or relative humidity) uncontrolled. With the introduction of variable speed technology, the speeds of compressor and supply air fan can be varied continuously so as to realize the simultaneous control of the indoor temperature and humidity. In this paper, the development of a novel control strategy based on PD law and fuzzy logic is reported. The compressor speed was adjusted directly according to the indoor air moisture content and supply air fan speed according to the indoor air temperature, respectively, to realize the simultaneous control of indoor air temperature and humidity. Controllability tests for the novel control strategy were carried out and the test results suggested that, although two control loops for temperature and humidity were significantly coupled, the simultaneous control of indoor temperature and humidity was achieved with respect to control accuracy and sensitivity