Search

The coalbed methane resources of the Gujiao Block are abundant, and the exploration degree is high. The gas production and water production of different CBM (coalbed methane) wells vary greatly. The average gas production of CBM wells in the study area is mostly less than 1000 m3/d, while the average water production is mostly less than 5 m3/d. The gas production of CBM wells near the core of the Malan syncline is relatively high. A series of large faults exist in the central and eastern parts of the study area, and CBM wells nearby produce more water but less gas. The salinity of water discharged from CBM wells ranges from 810.34 to 3115.48 mg/L, which is consistent with the trend of a gradual increase from north to south. The gas content distribution follows this same gradually increasing north to south trend. Coal thickness and buried depth have little effect on gas production, but have some effects on water production. The endogenous fracture system in the coal reservoir is extremely developed and the porosity and permeability of the reservoirs are low, which is not conducive to the migration and recovery of coalbed methane. The adsorption capacity of the coal sample is strong. However, the continuous uplift and denudation of the stratum from the middle Yanshanian to the Himalayan region are not conducive to the preservation and enrichment of coalbed methane. In addition, a series of large faults exist in this area, and the coal structures are broken. A large amount of coalbed methane is continually being released. Generally, structural and hydrological conditions affect the porosity, permeability, and gas content of coal reservoirs, thereby affecting the productivity of coalbed methane wells. The comprehensive analysis shows that the Xingjiashe well field in the southern part of the study area is a favorable area for CBM exploration and development.

The paraffin molecules in crude oil crystalize and precipitate out as the oil cools, resulting in a sharp increase in oil viscosity and further the gelation of the oil. The waxy crude oil gel exhibits complex rheological behaviors, such as viscoelasticity, yield stress, and thixotropy, posing challenges to the flow assurance of pipelines. Previous studies have verified that applying a high-voltage electric field to a flowing liquid oil can significantly reduce its viscosity. In this work, the electrorheological behaviors of waxy crude oil gel are explored by a stress-controlled rheometer equipped with in situ DC electric field manipulation. It is reported for the first time that the gel structure can be significantly weakened upon the application of an electric field for a duration of not less than 10 s, with the yield stress, storage modulus, loss modulus, and apparent viscosity reduced by up to 90%. In addition, the gel structure fracture is observed to transit from brittle-like to ductile-like. A stronger structure weakening effect can be obtained at a higher field strength and lower temperature. The structure weakening effect induced by the electric field can be maintained for a certain period of time after the removal of the electric field, with a recovery of yield stress and moduli less than 10% in 48 h. We hold the view that the electrorheological behaviors of waxy oil should be attributed to the weakened attraction between wax particles induced by the electric field.

Adhesive and cohesive fractures are the two possible modes of fracture during yield stress measurement of materials such as waxy oil gel. In this study, yield stress measurements were performed wit...

Treatment with pour point depressant (PPD) can significantly improve the cold flowability of waxy crude oil, enabling the safe and efficient transportation of waxy crude oils through pipelines. It ...

This paper proposed a hybrid hour-ahead forecast model, which combines multiple superimposed long and short term memory (LSTM) network and back-propagation neural network (BPNN), for the purpose of the load forecast on a building-level. The model (hybrid LSTM-BPNN) takes full consideration of the influence of the meteorological information, time information, the information of persons and devices and indoor thermal parameters. A method (LSTM-BPNN + BPNN) is further developed based on the forecasting advantages of sensible heat by hybrid LSTM-BPNN and latent heat by BPNN, in which the cooling load was split into sensible heat and latent heat to forecast separately. The results show that the method achieves the best performance for hour-ahead load forecasting compared with several classic forecasting models. An operation strategy based on the proposed LSTM-BPNN + BPNN method and LSTM model is applied to an improved ground source heat pump system integrated with cooling storage (GSHPs-CS) which was equipped with two storage tanks to achieve the variable volume control of stored chilled water. The system model is established by TRNSYS. Compared to conventional GSHPs-CS, the energy consumption and operating cost of the improved GSHPs-CS system were reduced by 11.5% and 7.5%, respectively.

Reconfigurable photonic integrated devices and circuits are very important for many applications. Among various mechanisms for realizing reconfigurability, thermo-optic effect is popular because of the availability for many materials, the design simplicity and the fabrication ease. In particular, silicon has a large thermo-optic coefficient as well as a high heat conductivity, and thus it is promising to realize efficient thermally-reconfigurable silicon photonic integrated devices and circuits. Recent progress is reviewed in this paper. First, thermally-tunable silicon photonic filters based on different structures are summarized, including microring resonators (MRRs) and MRRs-assisted Mach-Zehnder interferometers (MZIs). Second, silicon photonic switches based on MZIs and MRRs are reviewed. Finally, a review is given for thermally-reconfigurable silicon photonic integrated circuits developed for the applications in quantum photonics, microwave photonics, and optical interconnects.

A parametric collaborative optimization method for ground source heat pump-radiant ceiling (GSHP-RC) system is proposed to find the optimum setpoint combinations by maximizing system performance and reducing operating costs while ensuring indoor thermal comfort. The method integrates response surface method (RSM) and fast non-dominated sorting genetic algorithm (NSGA-II) to search the nonlinearity relationship between the controllable factors and the response factors and execute multi-objective optimization (MOO) progressively. A GSHP-RC system in an office building is investigated based on TRNSYS. Three controllable factors, the water supply temperature of radiant ceiling, the indoor set temperature and the water supply temperature of the heat pump, were used to analyze the influence mechanism on the system. The system performance, thermal comfort and economy are evaluated by seasonal performance factor (SPF), predicted mean vote (PMV) and the operating cost (OC). Two optimal cases were determined with the SPF of 3.741 and 3.734, the OC of CNY 23525 and 24613, and the PMV of 0.225 and -0.223 respectively. The optimization can realize 17.3% and 13.0% of the operating cost saving for the optimal cases respectively with the significant improvement in SPF under the premise of indoor thermal comfort compared with the reference case with conventional parameters.

Low-loss and compact optical waveguides are key for realizing various photonic integrated circuits with long on-chip delay lines, such as tunable optical delay lines, optical coherence tomography, and optical gyroscopes. In this paper, a low-loss and compact silicon photonic waveguide spiral is proposed by introducing broadened Archimedean spiral waveguides with a tapered Euler S-bend. A 100-cm-long waveguide spiral is realized with a minimal bending radius as small as 10 μm by using a standard 220-nm-thick silicon-on-insulator foundry process, and the measured propagation loss is as low as 0.28 dB/cm. Furthermore, the present waveguide spirals are used to realize a 10-bit tunable optical delay line, which has a footprint as small as 2.2 mm × 5.9 mm and a dynamic range of 5120 ps with a fine resolution of 10 ps.

Microwave photonic (MWP) filters using on-chip stimulated Brillouin scattering offer great potential for next-generation radio frequency (RF) applications due to the unprecedented high spectral resolution, flexible programmability, and ultra-wideband frequency agility. Although impressive functionalities have been reported, limited link performance, due to the amplification noise induced by the Brillouin gain process, hinders the practical deployment in existing RF applications. In this paper, we present the first comprehensive numerical and experimental study of chip-based Brillouin MWP bandpass filters implemented in a range of link configurations. In the experiments, key RF performance figures of merit, including link gain, noise figure, passband resolution, bandwidth tunability, and passband extinction of chip-based Brillouin filters are experimentally investigated and numerically analyzed. This comprehensive study points out a preferable filter scheme with optimized system-level performance. The numerical model developed in this paper allows for extrapolations to further improve the performance. The systematic work establishes a feasible design route for achieving high link-performance chip-based Brillouin microwave photonic bandpass filters.

To prepare polymer supported ionic liquids (PSILs) as effective catalysts for esterification, the free radical suspension copolymerization of vinylbenzyl chloride (VBC, monomer), styrene (St, monomer) and divinylbenzene (DVB, crosslinker) with the addition of n-heptane (porogen) was carried out for the fabrication of the porous polymer (PVD) microsphere as support, followed by the immobilization of sulfonic acid-functionalized ionic liquids by the successive treatment of benzimidazole (BIm), 1,3-propane sultone and sulfuric acid (H2SO4) or trifluoromethanesulfonic acid (CF3SO3H). The effects of the compositions of DVB and n-heptane on the internal structure of the polymer supports were investigated, and it was found that the support with 40 wt% DVB and 60 wt% n-heptane (with relative to the monomer) could endow the final PSILs with the relatively optimal catalytic performance. The preliminary experiment in the batch reactor indicated that PSILs herein exhibited higher catalytic activities than commercial Amberlyst 46 resin for the esterification of propanoic acid (PROAc) with n-propanol (PROOH). Consequently, the optimal PSILs catalyst, PVD-[Bim-SO3H]HSO4, was selected for further study in the batch reactive distillation column because of low cost and its ease of preparation. The yield of propyl ropionate (PROPRO) could reach up to 97.78% at the optimized conditions of PROOH/PROAc molar ratio (2:1) and catalyst dosage (2.0 wt%). The investigation of the reaction kinetic manifested that the calculated results of second order pseudo-homogeneous kinetic model were in good agreement with experimental values. The pre-exponential factor and activation energy were 4.12 × 107 L·mol−1·min−1 and 60.57 kJ·mol−1, respectively. It is worth noting that the PSILs catalyst could be simply recovered and reused with relatively satisfactory decrease in the catalytic activity, which made it an environmental friendly and promising catalyst in the industrial application.

Impedance spectroscopy (IS) is a widely used nondestructive and high-throughput experimental technique for the characterization of electrical properties of materials. In the petroleum industry, IS ...

Carotenoids represent a diverse class of aliphatic C40 molecules with a variety of applications in the food and pharmaceutical industries. Sporidiobolus pararoseus NGR produces various carotenoids, including torulene, torularhodin and β-carotene. Salt stress significantly increases the torulene accumulation of S. pararoseus NGR. However, little is known, about the molecular mechanisms underlying the increased torulene biosynthesis. In this work, we investigated the effects of NaCl treatment on the contents of carotenoids (both qualitatively and quantitatively) and transcriptome. A total of 12.3 Gb of clean bases were generated in six cDNA libraries. These bases were de novo assembled into 9,533 unigenes with an average length of 1,654 nt and N50 of 2,371 nt. Transcriptome analysis revealed that of 3,849 differential expressed genes (DEGs) in response to salt stress, 2,019 were up-regulated, and 1,830 were down-regulated. Among these DEGs, we identified three carotenogenic genes crtE, crtYB, and crtI. In addition, fourteen candidate genes were predicted to participate in the conversion from torulene to torularhodin. Our findings should provide insights into the mechanisms of carotenoid biosynthesis and salt-tolerance of S. pararoseus NGR.

Integrated photonics have experienced a rapid advance in the past few decades, and various materials/platforms for integrated photonic devices and circuits have been developed successfully, such as silicon-on-insulator, silicon nitride, and indium phosphide. The realization of on-chip polarization rotators (PRs) is often challenging as a planar optical waveguide usually has a very good ability of polarization maintaining. Waveguide gratings have attracted intensive attention because of the possibility of enabling the free spectral range-free optical filtering. The development of reconfigurable photonic integrated devices and circuits is important for making optical networks intelligent so that the bandwidth/channels can be utilized optimally and flexibly. MEMS-based silicon photonic devices also provide a good option for achieving ultra-low power consumption. It is also possible to develop some non-volatile silicon photonic devices with the help of phase-change materials. Therefore, in order to develop powerful silicon PICs in the future, it is useful to introduce other functional materials “X” and versatile structures on silicon.

Phase change material G e 2 S b 2 T e 5 (GST) has recently emerged as a highly promising candidate for photonic device applications owing to its high optical contrast, self-holding bi-stability, and fast material response. Here, we propose and analyze a 1 × 2 tunable switch using a GST embedded silicon microring resonator exploiting high optical contrast during GST phase change and a high thermo-optic coefficient of amorphous phase GST. Our device exhibits high extinction ratios of 25.57 dB and 18.75 dB at through and drop ports, respectively, with just a 1 µm long GST layer. The two states of the switch are realizable by electrically inducing phase change in GST. For post phase change from amorphous to crystalline and vice versa, the fall time down the 80% of phase transition temperature is ∼ 66 n s and ∼ 45 n s , respectively. The resonance wavelength shift per unit active length is 0.661 nm/µm, and the tuning efficiency is 1.16 nm/mW. The large wavelength tunability (4.63 nm) of the proposed switch makes it an attractive option for reconfigurable photonic integrated circuits.

Silicon photonics is recognized as one of the most promising platforms for on-chip optical interconnects. In order to further enhance the on-chip optical-interconnect link capacity, silicon photonic devices for advanced multiplexing technologies have been widely investigated, including wavelength-division-multiplexing (WDM), mode-divisionmultiplexing (MDM), as well as the hybrid multiplexing. This paper gives a review for our recent progresses in the development of silicon-based on-chip wavelength/mode-division-multiplexers.

LIDAR on a silicon chip holds strong potentials for LIDAR system solutions featuring low cost, small size, and high robustness. In line with this effort, on-chip circulators are of great interest as they bring significant benefit for system complexity reduction and SNR improvement by enabling the LIDAR transmitter and receiver to share a single common aperture. Here, we present our recent study on passive silicon photonics nonlinear switches as conditional circulators for LIDAR applications. We propose a device implementation to address the nonlinear switch working principle by controlling waveguide nonlinear coefficient using sub-wavelength gratings. This implementation is foundry-compatible using only regular passive silicon waveguide components and are fully demonstrated in the experiment. In addition, we propose a sub-splitting coupler-based switch potentially can achieve a better fabrication tolerance than sub-wavelength grating-based switch. This work builds up signal processing functions in silicon photonics technology for optical communication and sensing applications. In particular, for LIDAR applications, this work contributes to the critical components of important use, and the easy integration with other existing functions such as optical phased arrays and spectral filters pronounces the potential for LIDAR on a silicon chip.

A silicon integrated microwave photonic filter (IMPF) is demonstrated by utilizing a high-Q Euler-curve resonator with a large free-spectra range. The IMPF has a passband of 320 MHz and a tunable range of 8-27 GHz.

We propose the concept of silicon photonics beyond the singlemode regime with ultra- low-loss propagation of 0.065 dB/cm. The state-of-art micro-racetrack resonator, high-resolution microwave filter and 100-cm-long delayline are demonstrated with standard 220-nm-SOI (silicon- on-insulator) MPW-foundry processes.

We propose and demonstrate a novel silicon photonic spiral with a tapered-Euler-S-bend. A 100-cm-long waveguide spiral is realized with a bending radius as small as 10 μm, while the measured propagation loss is as low as 0.28 dB/cm.

We report thorough investigations of a photonic memory with phase change material embedded in a partially etched silicon waveguide, for operation at 1550 nm wavelength. Optical and thermal analyses are performed to study the performance of memory and the effect of deformity in G e 2 S b 2 T e 5 (GST) cells due to volume contraction upon crystallization. The presented approach has better performance than other approaches with GST integrated on top of or filled in a fully etched waveguide. It is shown that a high readout contrast of ∼ 33 d B with a low insertion loss of 0.79 dB is possible using an active volume of only 0.0079 µ m 3 . The photonic memory presented shows a low power consumption of 0.66 mW and 3.71 mW for switching the memory state from high to low and vice versa, respectively, with zero static power consumption. Using 100 ns and 10 ns pulses for phase transformation from amorphous to crystalline and that from crystalline to amorphous, the energy consumption is 82 pJ and 44.1 pJ, respectively.

Malaria is one of the deadliest infectious diseases threatening half of the world population. With the deterioration of the parasiticidal effect of the current antimalarials, novel approaches such as screening of more specific inhibitors and targeted delivery of drugs have been under intensive research. Herein, we prepare hollow mesoporous ferrite nanoparticles (HMFNs) of 200 nm with ferromagnetic properties using a one-pot hydrothermal reaction. A magnetically targeted drug-delivery system coloaded with artemisinin in the inner magnetite shell and heparin on the outer mesoporous shell (HMFN@ART@HEP) is developed. Specific targeting of the magnetic nanoparticles to the parasite-infected erythrocytes is achieved by the attraction between the HMFNs and hemozoin (paramagnetic), a vital metabolite of plasmodium in the erythrocytic stage. With the hemozoin production reaching the maximum during the schizont period of the parasite, HMFN@ART@HEPs are adsorbed to the infected red blood cells (iRBCs), which not only interferes with the release of merozoites but also significantly enhances the inhibitory efficacy due to the increased local concentration of artemisinin. Subsequently, the heparin coated on the surface of the nanoparticles can efficiently interfere with the invasion of freshly released merozoites to new RBCs through the specific interaction between the parasite-derived ligands and heparin, which further increases the inhibitory effect on malaria. As a cluster of heparin, heparin-coated nanoparticles provide stronger blocking capability than free heparin, resulting from multivalent interactions with surface receptors on merozoite. Thus, we have developed a HMFN-based delivery system with considerable antimalarial efficacy, which is a promising platform for treatment against malaria.

A dual-polarization waveguide superlattice is designed and realized by using 340 nm-thick silicon photonic waveguides. The silicon waveguide superlattices are formed with periodically arranged waveguides. Each period consists of five optical waveguides with core-widths designed optimally for minimizing the crosstalk among the optical waveguides. The optimized core-widths are 390 nm, 320 nm, 260 nm, 360 nm, and 300 nm when the separation between two adjacent waveguides is as small as 0.8 µm. With this design, the silicon waveguide superlattice works with low crosstalk (nearly –18 dB or less) for both polarizations within the range of 1530 nm to 1560 nm, which agrees well with the theoretical analysis.

Structural health monitoring (SHM) has been extensively used in civil infrastructures to assess structural condition and situation. Here, we develop a novel type of mechanical sensing technique using the structural instability of cylindrical cells detected by fiber Bragg grating (FBG). The cylinders are fabricated using a 3D printing technique, which are coiled by the FBG wires to detect the transverse deformation. Structural instability under axial compression is obtained in the experiments and the force–displacement relations are validated by the numerical simulations with satisfactory agreements. The wavelength variation of the FBG, caused by the structural instability, is observed and compared with the predefined threshold. Defining the variation larger than the threshold as “1” and smaller as “0”, the pattern recognition algorithm is used to convert the FBG results into binary data, which can, therefore, be analyzed to indicate the structural conditions. In the end, we envision the potential applications of the reported sensing technique, such as wireless sensors for structural health monitoring (SHM) in civil infrastructures.

A design rule for a Mach-Zehnder interferometer (MZI) sensor is presented, allowing tunable sensitivity by appropriately choosing the MZI arm lengths according to the formula given in this paper. The present MZI sensor designed by this method can achieve an ultra-high sensitivity, which is much higher than any other traditional MZI sensors. An example is given with silicon-on-insulator (SOI) nanowires and the device sensitivity is as high as 106 nm/refractive-index -unit (or even higher), by choosing the MZI arms appropriately. This makes it possible for one to realize a low-cost optical sensing system with a detection limit as high as 10&minus, 6 refractive-index-unit, even when a cheap optical spectrum analyzer with low-resolution (e.g., 1 nm) is used for the wavelength-shift measurement.

Under the guidance of “ensuring that children do not drop out of school due to poverty China has established a broad and universal subsidy system for poverty-stricken students in colleges and universities, which has achieved phased results. However, during the implementation, there are still some bad phenomena such as “fake poverty-stricken students This paper will focus on the application of big data technology to solve the above problems through technical means. It also studies the optimization of the system from three aspects: logical structure design, physical structure design and flow chart design of the big data service platform for poverty-stricken college students.

We present a silicon racetrack-resonator based on a modified Euler curve for high-performance microwave photonic filters. It has a high Q-factor of 7×105, free spectral range of 0.73 nm, and tuning range of 92 GHz. © 2020 The Author(s)

All-optical silicon-photonics-based LiDAR systems allow for desirable features in scanning resolution and speed, as well as leverage other advantages such as size, weight, and cost. Implementing optical circulators in silicon photonics enables bidirectional use of the light path for both transmitters and receivers, which simplifies the system configuration and thereby promises low system cost. In this work, to the best of our knowledge, we present the first experimental verification of all-passive silicon photonics conditional circulators for monostatic LiDAR systems using a nonlinear switch. The proposed silicon nonlinear interferometer is realized by controlling signal power distribution with power-splitting circuits, allowing the LiDAR transmitter and receiver to share the same optical path. Unlike the traditional concept requiring a permanent magnet, the present device is implemented by using common silicon photonic waveguides and a standard foundry-compatible fabrication process. With several additional phase shifters, the demonstrated device exhibits considerable flexibility using a single chip, which can be more attractive for integration with photodetector arrays in LiDAR systems.