A Sub-1-V, 350-uW, 6.5-dB Integrated NF Low-IF Receiver Front-End for IoT in 28-nm CMOS

This letter presents a highly efficient low-intermediate frequency receiver front-end for Internet-of-Things applications. The lownoise trans-impedance amplifier (LNTA) combines a transformer-based network for scaling up the source impedance together with passive gmboosting and current-reuse techniques to achieve better noise and 12× current saving compared with a common-gate (CG) stage. A complex channel-selection filter with center frequency and passband of 2 and 1.4 MHz, respectively, is implemented after the passive mixer with a gmboosted CG stage. Built in 28-nm CMOS, the proposed receiver occupies an active area of 0.1 mm 2 , it is supplied with 0.9 V and consumes only 350 μW, while showing a minimum NF of 6.2 dB at the channel of interest. The RF performance of the proposed receiver is very competitive with the state-of-the-art ultralow-power receivers, while it consumes the lowest power

Water Resources Contribution To Economic Growth In Erdos City: Model And Demonstration

Erdos City has been one of the fastest growing economic regions in China in the past twenty years, whose average annual economic growth rate has exceeded 20%. However, water resources shortage is becoming increasingly significant in constraint on social development and has gradually developed to be one of primary weakest factors. Based on the analysis of main factors promoting economic growth in Erdos City with Cobb-Douglas production function in economics, the economic growth model involving water resources availability and coal output has been established and the data conversion method considering water consumption efficiency and water consumption structural change has been proposed. In this way, it has made up for the deficiency of failing to fully consider the contribution of water consumption efficiency improvement and water consumption structural change to economic growth in the past researches. What have been discovered in the simulation and analysis of water resources contribution to economic growth in Erdos City from 1980 to 2010 as follows: (1) Water resources average contribution rate to economic growth in Erdos City in the past 30 years is 8.26%; (2) Consumption efficiency and structural change of water resources have played an important role in promoting economic development; (3) Water resources contribution to economic growth has shown a gradually increasing trend that the average contribution rates in the three decades are 1.87%, 9.69% and 10.09% respectively. The trend is closely connected with constantly increased gross water consumption, obvious improvement of water consumption efficiency and gradual upgrading of water consumption structure in the local area. It also has reflected that water resources have played an increasingly significant role in constraint on regional economic social development

Thingking and utilization technology of coalbed methane in soft and low permeability coal seams in Huainan Mining Area

In order to solve the problems that restrict the efficient development of coalbed methane resources under the conditions of soft and low permeability outburst coal seams in Huainan Mining Area, such as complex coal seam structure, multi-source gas emission, rapid decline of drainage flow, high rock roadway and drilling costs, and low (ultra-low) concentration coalbed methane utilization rate, six key technologies suitable for the coordinated development mode of coal and coalbed methane under the condition of coal seam group mining in Huainan mining area are put forward, namely: coalbed methane extraction technology of ground level staged fracturing wells, shield rapid construction technology of coalbed methane extraction roadways, enhanced extraction technology of underground soft coalbed methane, coalbed methane extraction technology of pressure relief in ground mining area, the construction technology of "replacing roadways with holes", and cascade utilization technology of low concentration coalbed methane. The application of supporting key technologies shows that staged fracturing technology and refined drainage and production technology of roof horizontal wells in broken and soft coal seam have effectively improved the pre pumping production of coalbed methane; The full face hard rock roadheader in deep coal mine roadway greatly improves the roadway excavation efficiency, realizing the automation and less humanization of hard rock excavation; Sand adding of hydraulic fracturing and ultra-high hydraulic slotting have realized pressure relief and permeability enhancement in large areas underground coal mine; Type III and IV surface mining area wells can replace the roof high drainage roadway in the treatment of pressure relief gas in coal seam group mining, and reduce the coalbed methane drainage intensity of other measures; The technology of "replacing roadways with holes" has significantly improved the quality of successful directional drilling at middle and high levels in complex roof; Cascade utilization technology of low concentration coalbed methane has greatly reduced the emission of coalbed methane. The six key technologies have guaranteed the safe production in Huainan mining area, and comprehensively improved the output of coal and coalbed methane and the utilization level of coalbed methane. Six key technologies ensure the safe production in Huainan mining area, and comprehensively improved the output of coal and coalbed methane and the utilization level of coalbed methane. Finally, in view of the problems such as high operation cost, low production, small scope of hydraulic fracturing coal reservoir reconstruction technology for surface horizontal wells, and the risk of breakage of mining wells, and small scale of cascade utilization of ultra-low concentration coalbed methane, the development direction of deep CBM precise geological guidance, super large scale efficient reservoir volume transformation, pumping effect evaluation technology, stable and continuous pumping technology of surface wells in mining areas, underground large area intelligent hydraulic enhanced permeability technology, "one well with multiple uses" collaborative pumping CBM technology, and full concentration CBM comprehensive utilization technology are proposed

Study on Pre Pumping and Outburst Elimination Technology of “one hole and two elimination” in Bedding Directional Long Drilling

Aiming at the problem of gas control in the working face and the roadway to be excavated at the same time due to the small construction length of bedding borehole under the condition of the occurrence of soft coal, a technology of "one hole and two elimination" pre-drainage to eliminate gas outburst by using air screw motor drilling was put forward, and the field test was carried out in the 17102(3) working face of Pansu Coal Mine.The results show that this technology can effectively control the borehole trajectory, ensure the uniform and reasonable range of borehole outburst elimination, solve the problems of long gas treatment cycle caused by the construction of gas treatment roadway, improve the effective drainage time of borehole, ensure enough time and space for gas treatment, and be beneficial to the mining and replacement of mine

Polyethyleneimine-Based Drug Delivery Systems for Cancer Theranostics

With the development of nanotechnology, various types of polymer-based drug delivery systems have been designed for biomedical applications. Polymer-based drug delivery systems with desirable biocompatibility can be efficiently delivered to tumor sites with passive or targeted effects and combined with other therapeutic and imaging agents for cancer theranostics. As an effective vehicle for drug and gene delivery, polyethyleneimine (PEI) has been extensively studied due to its rich surface amines and excellent water solubility. In this work, we summarize the surface modifications of PEI to enhance biocompatibility and functionalization. Additionally, the synthesis of PEI-based nanoparticles is discussed. We further review the applications of PEI-based drug delivery systems in cancer treatment, cancer imaging, and cancer theranostics. Finally, we thoroughly consider the outlook and challenges relating to PEI-based drug delivery systems

Response Characteristics of Coal-Like Material Subjected to Repeated Hydraulic Fracturing: An Evaluation Based on Real-Time Monitoring of Water Injection Pressure and Roof Stress Distribution

Conventional hydraulic fracturing has several disadvantages, including a short effective extraction time and low fracture conductivity during long-term extraction. Aiming at overcoming these shortcomings, a similar simulation test of repeated hydraulic fracturing was conducted in this study, and the evolutionary rules regarding the injection water pressure and stress distribution of the coal seam roof during this repeated hydraulic fracturing were revealed. The research results show that after multiple hydraulic fracturing, the number of cracks in the coal seam and the range of fracturing influence have increased significantly. As the number of fracturing increases, the initial pressure required for cracking decreases. The highest water injection pressure of the first fracturing was 2.8 MPa, while the highest water injection pressures of the second and third fracturing were 2.7 MPa and 2.4 MPa, respectively. As the number of fracturing increases, the area of increased stress will continue to expand. After the first fracturing, the impact radius of fracturing is 100 cm. After the second fracturing, the radius of influence of fracturing expanded to 150 cm. When the third fracturing was over, the radius of influence of the fracturing expanded to approximately 250 cm. It can be seen that, compared with conventional hydraulic fracturing, repeated hydraulic fracturing shows better fracturing effect. The research results can be used as a basis for repeated hydraulic fracturing field tests to increase coal seam permeability

Three-Dimensional Inverse Design of Low Specific Speed Turbine for Energy Recovery in Cooling Tower System

A three-dimensional inverse design of a low specific speed turbine is studied, and a set of design criteria for low specific speed turbine runner is proposed, including blade loading distributions and blade lean angles. The characteristics of the loading parameters for low specific speed turbine runner are summarized by analyzing the suction performance of different loading positions, loading slopes and blade lean angles based on the orthogonal experiment design and range analysis. It is found that the blade loading distribution at the band plays a more important role than it does at the crown and it should be fore loaded for both band and crown. The blade lean angle at the blade leading edge should be negative. Then, the blade is optimized through the inverse method by fixing blade lean angle, based on the response surface method. After seeking the optimal value of the response surface function, the optimal result of the design parameters is obtained, which is in conformity with the design criteria and verifies the rationality of the established design criteria for low specific speed turbine

Evaluation and Improvement of No-Ground-Truth Dual Band Algorithm for Shallow Water Depth Retrieval: A Case Study of a Coastal Island

Conventional bathymetric inversion approaches require bathymetric data as ground truth to obtain shallow water depth from high spatial resolution remote sensing imagery. Thus, bathymetric mapping methods that do not require inputs from in situ measurements are highly desirable. In this paper, we propose a dual-band model improvement method and evaluate the performance of this novel dual-band model approach to obtain the underwater terrain around a coastal island by using four WorldView-2/3 imageries. Then, we validate the results through changing water column properties with the Kd multiple linear regression model simulated by Hydrolight. We multiply the best coefficient and blue–green band value with different substrates on the pixels, which sample along the coastal line and isobath. The results show that the mean bias of inversed depth ranges from 1.73 to 2.96 m in the four imageries. The overall accuracy of root mean square errors (RMSEs) is better for depths shallower than 10 m, and the average relative error is 11.89%. The inversion accuracy of this new model is higher than Lee’s classical Kd model and has a wider range of applications than Chen’s dual-band model. The no-ground-truth dual-band algorithm has higher accuracy than the other log-ratio methods mentioned in this paper

Effect of the One-to-Many Relationship between the Depth and Spectral Profile on Shallow Water Depth Inversion Based on Sentinel-2 Data

In shallow water, Sentinel-2 multispectral imagery has only four visible bands and limited quantization levels, which easily leads to the occurrence of the same spectral profile but different depth (SSPBDD) phenomenon, resulting in a one-to-many relationship between water depth and spectral profile. Investigating the impact of this relationship on water depth inversion models is the main objective of this paper. The Stumpf model and three machine learning models (Random Forest, Support Vector Machine, and Mixture Density Network) are employed, and the performance of these models is analysed based on the spatial distribution of the training dataset and the input information composition of these models. The results show that the root mean square errors (RMSEs) of the depth inversion of Random Forest and Support Vector Machine are significantly affected by the spatial distribution of the training dataset, while minimal effects are observed for the Stumpf model and the Mixture Density Network model. The SSPBDD phenomenon is widespread in Sentinel-2 images at all depths, particularly between 5 m and 15 m, with most of the depth maximum difference of the SSPBDD pixels ranging from 0 to 5 m. The SSPBDDs phenomenon can significantly reduce the inversion accuracy of any model. The number and the depth maximum difference of the SSPBDDs pixels are the main influencing factors. However, by increasing the visible spectral information and the spatial neighbourhood information in the input layer of machine learning models, the inversion accuracy and stability of the models can be improved to a certain extent. Among the models, the Mixture Density Network achieves the best inversion accuracy and stability