The status of exploitation techniques of natural gas hydrate

Natural gas hydrate(NGH)has been widely considered as an alternative form of energy with huge potential,due to its tremendous reserves,cleanness and high energy density.Several countries involving Japan,Canada,India and China have launched national projects on the exploration and exploitation of gas hydrate resources.At the beginning of this century,an early trial production of hydrate resources was carried out in Mallik permafrost region,Canada.Japan has conducted the first field test from marine hydrates in 2013,followed by another trial in 2017.China also made its first trial production from marine hydrate sediments in 2017.Yet the low production efficiency,ice/hydrate regeneration,and sand problems are still commonly encountered;the worldwide progress is far before commercialization.Up to now,many gas production techniques have been proposed,and a few of them have been adopted in the field production tests.Nevertheless,hardly any method appears really promising;each of them shows limitations at certain conditions.Therefore,further efforts should be made on the economic efficiency as well as sustainability and environmental impacts.In this paper,the investigations on NGH exploitation techniques are comprehensively reviewed,involving depressurization,thermal stimulation,chemical inhibitor injection,CO2–CH4 exchange,their combinations,and some novel techniques.The behavior of each method and its further potential in the field test are discussed.The advantages and limitations of laboratory studies are also analyzed.The work could give some guidance in the future formulation of exploitation scheme and evaluation of gas production behavior from hydrate reservoirs.

Safety and survival outcomes of transanal natural orifice specimen extraction using prolapsing technique for patients with middle-to low-rectal cancer

Objective:The transanal approach to specimen collection,combined with the prolapsing technique,is a wellestablished and minimally invasive surgery for treating rectal cancer.However,reports on outcomes for this approach are sparse.We compared short-and long-term outcomes of conventional laparoscopic surgery(CLS)vs.transanal natural orifice specimen extraction(NOSE)using the prolapsing technique for patients with middle-to low-rectal cancer.Methods:From January 2013 to December 2017,we enrolled consecutive patients with middle-to low-rectal cancer undergoing laparoscopic anterior resection.Totally,50 patients who underwent transanal NOSE using the prolapsing technique were matched with 50 patients who received CLS.Clinical parameters and survival outcomes between the two groups were compared.Results:Estimated blood loss(29.70±29.28 vs.52.80±45.09 mL,P=0.003),time to first flatus(2.50±0.79 vs.2.86±0.76,P=0.022),time to liquid diet(3.62±0.64 vs.4.20±0.76 d,P<0.001),and the need for analgesics(22%vs.48%,P=0.006)were significantly lower for the NOSE group compared to the CLS group.The incidences of overall complications and fecal incontinence were comparable in both groups.After a median follow-up of 44.52 months,the overall local recurrence rate(6%vs.5%,P=0.670),3-year disease-free survival(86.7%vs.88.0%,P=0.945)and 3-year overall survival(95.6%vs.96.0%,P=0.708),were not significantly different.Conclusions:For total laparoscopic rectal resection,transanal NOSE using the prolapsing technique is effective and safe,and associated with less trauma and pain,a faster recovery,and similar survival outcomes compared to CLS.

On Solving TM_(0n) Modal Excitation in a Ka-Band Overmoded Circular Waveguide by the Conservation of Complex Power Technique

To measure the radiation properties of relativistic diffraction generator （RDG） in Ka-band, a TMon modal excitation model is established, which consists of an overmoded circular waveguide and a coaxial line feeding probe. Using the transverse E-field mode matching and the conservation of complex power technique （CCPT）, we deduce the scattering matrix at coaxial line to coaxial line and coaxial line to circular waveguide junctions. Then using the overall cascaded junction scattering matrix, the numerical results for the reflection coefficient of the coaxial line and the power distribution of TMon multi-modal are presented. The numerical results are in agreement with HFSS simulation results and experimental results. The analysis shows that by choosing the appropriate position of coaxial line probe, the power proportion of the device operating mode excited in circular waveguide could be the largest.

RADIOACTIVE OR NATURAL TRACER TECHNIQUES FOR LEAK DETERMINING OF DAM ABUTMENT

Infiltration and localization of preferential infiltration zones at the dam abutment are measured using radioactive tracer tests of flow in boreholes, meanwhile interconnection between boreholes and the energing water points is analysed. The theory and practice of radioactive tracer synthetic detective method are described to give methods and calculation formulae used under the condition of stable flow in single well to measure permeability coefficient and hydrostatic heads. Major single hole techniques including measurement for seepage line, velocity, rate of seepage flow and relationship of recharge of groundwater in aquifers are introduced briefly.The possibilities offered by natural tracers are analysed, including electric-conduct,pH-value and temperature of water as well as stable isotopes (D, 18O) and tritium.Furthermore, the sensibilities of this theory and methods were confirmed by detecting seepage flow field of Xinanjiang Dam.

Study on the 3D Seismic Data Field Hybrid Rendering Technique of Natural Gas Hydrate and Its Application

3D visualization technology is a tool used for displaying, describing, and understanding the characteristics of geologic bodies, and features high efficiency, objective accuracy, visual expression, etc. In this paper, the man-machine interactive interpretation and 3D visualization technology rapidly displaying and analyzing the 3D seismic data of hydrate ore volume is researched and developed using the hybrid rendering technique. Through the integrated interpretation on the 3D space structure, stratum, and seismic attributes, the visualized multi-attribute superimposition analysis is implemented for describing the spatial distribution characteristics of hydrate ore volume and exquisitely describing the subtle geological characteristics of hydrate ore volume. By the hybrid rendering technique, authentication and interpretation are provided for the geological exploration work, so as to greatly enhance the visualization and accuracy of the geological analysis, and also provide a good decision-making foundation for the subsequent development of resources.

New Form of Legendre Polynomials Obtained by Virtue of Excited Squeezed State and IWOP Technique in Quantum Optics

Using the technique of integration within an ordered product of operators and the intermediate coordinatemomentum representation in quantum optics, as well as the excited squeezed state we derive a new form of Legendre polynomials.

Modal Parameters Identification of A Real Offshore Platform From the Response Excited by Natural Ice Loading

This paper investigates the possibility of utilizing response from natural ice loading for modal parameter identification of real offshore platforms.The test platform is the JZ20-2 MUQ jacket platform located in the Liaodong Bay,China.A field experiment is carried out in winter season,as the platform is excited by floating ices.The feasibility is demonstrated by the acceleration response of two different segments.By the SSI-data method,the modal frequencies and damping ratios of four structural modes can be successfully identified from both segments.The estimated information from both segments is almost identical,which demonstrates that the modal identification is trustworthy.Furthermore,by taking the Jacket platform as a benchmark,the numerical performance of five popular time-domain EMA methods is systematically compared from different viewpoints.The comparisons are categorized as:(1)stochastic methods versus deterministic methods;(2)high-order methods versus low-order methods;(3)data-driven versus covariance-driven stochastic subspace identification methods.

Flight Flutter Modal Parameters Identification with Atmospheric Turbulence Excitation Based on Wavelet Transformation

In view of the feature of flight flutter test data with atmospheric turbulence excitation, a method which combines wavelet transformation with random decrement technique for identifying flight flutter modal parameters is presented. This approach firstly uses random decrement technique to gain free decays corresponding to the acceleration response of the structure to some non-zero initial conditions. Then the continuous Morlet wavelet transformation of the free decays is performed; and the Parseval formula and residue theorem are used to simplify the transformation. The maximal wavelet transformation coefficients in different scales are searched out by means of band-filtering characteristic of Morlet wavelet, and then the modal parameters are identified according to the relationships with maximal modulus and angle of the wavelet transform. In addition, the condition of modal uncoupling is discussed according to variation trend of flight flutter modal parameters in the flight flutter state. The analysis results of simulation and flight flutter test data show that this approach is not only simple, effective and feasible, but also having good noise immunity.

Discussion on Green Development of Fenlong for Yield Increase, Quality Enhancing, Water Retaining and Multiple Use of Natural Resources

Fenlong green ecological agriculture technology （Fenlong technology）, a new smash ridging farming method developed by Guangxi Academy of Agdcultural Sciences, has been elected as the recommended cultivation technique by the Ministry of Agriculture of China. It replaces the traditional plowshare with spiral drill, and its tilth depth is twice deeper than that by tractor tilthing. It also extends soil nutrient, moisture, oxygen and microorganism, the so-called ＂Four pools＂. Soil nutrient, oxygen, microorganism, light and rainfall use ratio is increased by 10%-100%, creating a platform for natural increase of more than 10% of crop yield. Its application to over 20 kinds of crops in 21 provinces has proved that the yield increases 10-30% with quality enhancing 5% and double water retaining capacity but no more input. When the application area of Fenlong could reach 67 million hm2, the amount of fertilizer can be reduced by 40-50 billion kg, saving 120-150 billion Yuan. In this paper, we put forward the strategy of ＂4＋1＂ （arable, saline-alkali soil, grasslands, Sponge City ＋ rivers） green development in China, and deepened the Fenlong cultivated tilled layer from 16.5 cm to 35 cm for 67 million hm2 arable land, ridged 13.3 million hm2 of saline-alkali soil for 35 cm, and also 35 cm for 67 million hm2 degraded steppe, which could have the following 3 effects： first, the 147 million hm2 of land with Fenlong cultivation could increase loosing soil to 315.491 billion m3, in＊ creasing by 159.26% for 120 million hm2 of arable land with the average tilled layer of 16.5 cm, which has loosing soil of only 198.1 billion m3, that is, the space of the land increases 1.6 times. Second, every hectare of plowland could store up to 450 m3/hm2 of natural rainfall, and the unused 60 m3 of saline-alkali soil and grasslands could store water of 102 billion m3, showing an increase of over 88.89% for the current plowland storage of 54 billion m3 at now, that is, double the natural rainfall storage capacity. Third, the two multiple increase of natural resources application can bring trillions of resource activation, environmental cleaning, food security, citizens, health, economic, ecological and social benefits, and makes the Chinese nation move forward in green development. Its application in ＂big scientific research＂ and ＂One Belt And One Road＂ will contribute Chinese strength to the world.

Short-term efficacy of natural orifice specimen extraction surgery for low rectal cancer

BACKGROUND This case-control study compared the short-term clinical efficacy of natural orifice specimen extraction surgery(NOSES) using a prolapsing technique and the conventional laparoscopic-assisted approach for low rectal cancer.AIM To further explore the application value of the transanal placement of the anvil and to evaluate the short-term efficacy of NOSES for resecting specimens of low rectal cancer, as well as to provide a theoretical basis for its extensive clinical application.METHODS From June 2015 to June 2018, 108 consecutive laparoscopic-assisted low rectal cancer resections were performed at our center. Among them, 26 specimens were resected transanally using a prolapsing technique(NOSES), and 82 specimens were resected through a conventional abdominal wall small incision(LAP). A propensity score matching method was used to select 26 pairs of matched patients, and their perioperative data were analyzed.RESULTS The baseline data were comparable between the two matched groups. All 52 patients underwent the surgery successfully. The operative time, blood loss,number of harvested lymph nodes, postoperative complication rate,circumferential margin involvement, postoperative follow-up data, and postoperative anal function were not statistically significant. The NOSES group had shorter time to gastrointestinal function recovery(2.6 ± 1.0 d vs 3.4 ± 0.9 d, P= 0.006), shorter postoperative hospital stay(7.1 ± 1.7 d vs 8.3 ± 1.1 d, P = 0.003),lower pain score(day 1: 2.7 ± 1.8 vs 4.6 ± 1.9, day 3: 2.0 ± 1.1 vs 4.1 ± 1.2, day 5: 1.7± 0.9 vs 3.3 ± 1.0, P < 0.001), a lower rate of additional analgesic use(11.5% vs61.5%, P = 0.001), and a higher satisfaction rate in terms of the aesthetic appearance of the abdominal wall after surgery(100% vs 23.1%, P < 0.001).CONCLUSION NOSES for low rectal cancer can achieve satisfactory short-term efficacy and has advantages in reducing postoperative pain, shortening the length of postoperative hospital stay, and improving patients' satisfaction in terms of a more aesthetic appearance of the abdominal wall.

OPTIMAL INTERIOR PARTIAL REGULARITY FOR NONLINEAR ELLIPTIC SYSTEMS UNDER THE NATURAL GROWTH CONDITION:THE METHOD OF A-HARMONIC APPROXIMATION

In this article, the authors consider the nonlinear elliptic systems under the natural growth condition. They use a new method introduced by Duzaar and Grotowski, for proving partial regularity for weak solutions, based on a generalization of the technique of harmonic approximation. And directly establish the optimal Holder exponent for the derivative of a weak solution.

Operational Modal Analysis of a Ship Model in the Presence of Harmonic Excitation

A ship is operated under an extremely complex environment, and waves and winds are assumed to be the stochastic excitations. Moreover, the propeller, host and mechanical equipment can also induce the harmonic responses. In order to reduce structural vibration, it is important to obtain the modal parameters information of a ship. However, the traditional modal parameter identification methods are not suitable since the excitation information is difficult to obtain. Natural excitation technique-eigensystem realization algorithm （NExT-ERA） is an operational modal identification method which abstracts modal parameters only from the response signals, and it is based on the assumption that the input to the structure is pure white noise. Hence, it is necessary to study the influence of harmonic excitations while applying the NExT-ERA method to a ship structure. The results of this research paper indicate the practical experiences under ambient excitation, ship model experiments were successfully done in the modal parameters identification only when the harmonic frequencies were not too close to the modal frequencies.

Energy Transfer Pathways in Reaction Center upon Femtosecond Excitation of Accessory Bacteriochlorophylls

The energy transfer pathways from the excited accessorybacteriochlorophylls (B*) within native and modified (pheophytin-exchanged) reaction center isolated from Rhodobactersphaeroides (RS601) have been investigated by using the femtosecond pump-probe technique. For native RS601, B* decays with time constant of 240 fs, followed by a partial recovery of the ground state bleaching with time scale of about 2 ps. In modified RS601(Phe), however, B* decays with time constant of 800 fs for magic angle (54.7°) polarization configuration. In addition to the general assumption of energy transfer pathway from B* to the special pair P, an alternative pathway for energy transfer probably operates as well.

Nonlinear Dynamics of Viscoelastic Pipe Conveying Pulsating Fluid Subjected to Base Excitation

Based on the Euler-Bernoulli beam theory and Kelvin-Voigt model,a nonlinear model for the transverse vibration of a pipe under the combined action of base motion and pulsating internal flow is established.The governing partial differential equation is transformed into a nonlinear system of fourth-order ordinary differential equations by using the generalized integral transform technique(GITT).The effects of the combined excitation of base motion and pulsating internal flow on the nonlinear dynamic behavior of the pipe are investigated using a bifurcation diagram,phase trajectory diagram,power spectrum diagram,time-domain diagram,and Poincare map.The results show that the base excitation amplitude and frequency significantly affect the dynamic behavior of the pipe system.Some new resonance phenomena can be observed,such as the period-1 motion under the base excitation or the pulsating internal flow alone becomes the multi-periodic motion,quasi-periodic motion or even chaotic motion due to the combined excitation action.

A Novel Auto-Annotation Technique for Aspect Level Sentiment Analysis

In machine learning,sentiment analysis is a technique to find and analyze the sentiments hidden in the text.For sentiment analysis,annotated data is a basic requirement.Generally,this data is manually annotated.Manual annotation is time consuming,costly and laborious process.To overcome these resource constraints this research has proposed a fully automated annotation technique for aspect level sentiment analysis.Dataset is created from the reviews of ten most popular songs on YouTube.Reviews of five aspects—voice,video,music,lyrics and song,are extracted.An N-Gram based technique is proposed.Complete dataset consists of 369436 reviews that took 173.53 s to annotate using the proposed technique while this dataset might have taken approximately 2.07 million seconds(575 h)if it was annotated manually.For the validation of the proposed technique,a sub-dataset—Voice,is annotated manually as well as with the proposed technique.Cohen’s Kappa statistics is used to evaluate the degree of agreement between the two annotations.The high Kappa value(i.e.,0.9571%)shows the high level of agreement between the two.This validates that the quality of annotation of the proposed technique is as good as manual annotation even with far less computational cost.This research also contributes in consolidating the guidelines for the manual annotation process.

Using Speech Recognition in Learning Primary School Mathematics via Explain, Instruct and Facilitate Techniques

The application of Information and Communication Technologies has transformed traditional Teaching and Learning in the past decade to computerized-based era. This evolution has resulted from the emergence of the digital system and has greatly impacted on the global education and socio-cultural development. Multimedia has been absorbed into the education sector for producing a new learning concept and a combination of educational and entertainment approach. This research is concerned with the application of Window Speech Recognition and Microsoft Visual Basic 2008 Integrated/Interactive Development Environment in Multimedia-Assisted Courseware prototype development for Primary School Mathematics contents, namely, single digits and the addition. The Teaching and Learning techniques—Explain, Instruct and Facilitate are proposed and these could be viewed as instructors’ centered strategy, instructors’—learners’ dual communication and learners' active participation. The prototype is called M-EIF and deployed only users' voices;hence the activation of Window Speech Recognition is required prior to a test run.

Effects of Food Diet Preparation Techniques on Radionuclide Intake and Its Implications for Individual Ingestion Effective Dose in Abeokuta, Southwestern Nigeria

The radioactivity measurements in food crops and their diet derivatives and farm soil samples from Abeokuta, one of the elevated background radiation areas in Nigeria have been carried out in order to determine the concentration levels of natural radionuclides (40K, 226Ra and 232Th). The activity concentrations of the natural radionuclides in the samples were determined via gamma-ray spectrometry using a 76 mm × 76 mm NaI(Tl) detector. Different common food crops representing the major sources of dietary requirements to the local population were collected for the measurements. The collected food crops were prepared into their different derivable composite diets using preparation techniques locale to the population. Using available food consumption data and the activity concentrations of the radionuclides, the ingestion effective doses were evaluated for the food crops and diet types per preparation techniques. For the tuberous food crop samples, the annual ingestion effective doses in the raw and different composite diets were 0.02 - 0.04 μSv and cumulatively 0.04 - 0.05 μSv while in the non-tuberous crops the doses were 0.44 - 0.70 μSv and cumulatively greater than 1 μSv respectively. Results of the study indicate that method of diet preparation is seen to play a major role in population ingestion dose reduction especially for tuberous crops than in non-tuberous crops. The study also showed that more ingestion dose could be incurred in diets prepared by roasting techniques. The result of the study will serve as a useful radiometric data for future epidemiological studies in the area and for food safety regulations and policy implementations in the country.

Seismic fine imaging and its significance for natural gas hydrate exploration in the Shenhu Test Area, South China Sea

Shenhu area in South China Sea includes extensive collapse and diapir structures,forming high-angle faults and vertical fracture system,which functions as a fluid migration channel for gas hydrate formation.In order to improve the imaging precision of natural gas hydrate in this area,especially for fault and fracture structures,the present work propose a velocity stitching technique that accelerates effectively the convergence of the shallow seafloor,indicating seafloor horizon interpretation and the initial interval velocity for model building.In the depth domain,pre-stack depth migration and residual curvature are built into the model based on high-precision grid-tomography velocity inversion,after several rounds of tomographic iterations,as the residual velocity field converges gradually.Test results of the Shenhu area show that the imaging precision of the fault zone is obviously improved,the fracture structures appear more clearly,the wave group characteristics significantly change for the better and the signal-to-noise ratio and resolution are improved.These improvements provide the necessary basis for the new reservoir model and field drilling risk tips,help optimize the favorable drilling target,and are crucial for the natural gas resource potential evaluation.

REGULARITY FOR NONLINEAR ELLIPTIC SYSTEMS WITH DINI COEFFICIENTS UNDER NATURAL GROWTH CONDITION FOR THE CASE:1

In this article,we consider interior regularity for weak solutions to nonlinear elliptic systems of divergence type with Dini continuous coefficients under natural growth condition for the case 1〈m〈 2.All estimates in the case of m≥2 is no longer suitable,and we can’t obtain the Caccioppoli’s second inequality by using these techniques developed in the case of m≥2.But the Caccioppoli’s second inequality is the key to use A-harmonic approximation method.Thus,we adopt another technique introduced by Acerbi and Fcsco to overcome the difficulty and we also overcome those difficulties due to Dini condition.And then we apply the A-harmonic approximation method to prove partial regularity of weak solutions.

Cartographic-Environmental Analysis of the Landscape in Natural Protected Parks for His Management Using GIS.Application to the Natural Parks of the“Las Batuecas-Sierra de Francia”and“Quilamas”(Central System,Spain)

In this work we report a methodological procedure with an integrated physical-perceptual approach that allows units of landscape in protected natural areas to be differentiated. First, indirect methods were applied by means of a mapping procedure, which identified the physical components of major relevance. We then generated maps of natural units, anlyzing the “printed” landscape of a territory. Secondly, we developed direct methods to identify and describe the reresentative elements of the landscape, analyzing the “perceived” landscape. The identification and delimitation of these landscape units with geographical information systems provide detailed maps facilitate the tasks of planning and management. The procedure was validated by means of its application in two protected natural spaces. The treatment used here considers landscape not only as an aesthetic element but also as something “live” elaborating maps that should be of use in land planning and management of natural areas.