Automated Dimensioning Method of Engineering Drawings for Mechanical Products Based on Curve Chain

An automated method based on the curve chain was proposed for dimensioning of engineering drawings for the mechanical products.According to the internal relation between the features of 3D model feature and elements of 2D drawing,the curve chain was established to reflect the geometric topological structure between the elements.It divides the dimensions into the absolute dimensions within the cure chain and the relative dimensions between the curve chains.The parallel and lengthy relationship between the drawing elements of the constructed X and Y parallel matrix was solved to remove redundant elements in the curve chain and labeled the absolute dimensions of the remaining valid elements.The average minimum weight coefficient was introduced to judge the dependence on the relative dimensions between curve chains.Through the analysis of the overlap between the circular rectangular areas,including all the absolute dimensions of the curve chains,overlapping curve chains were merged,and their dimensions were rearranged to avoid the cross interference between them.The method was seamlessly integrated into the drafting module of product design software NX,and it developed an automated dimensioning system.The examples show that the system has excellent interactivity and robustness in the dimensioning of product engineering drawings.The dimension information is complete,accurate and reliable.

Zhangjiakou Mechanical Products

Cuban President Fidel Castro highly praised the products of Zhangjiakou’s Xuanhua Building Machinery Plant at a national conference in 1990. On the president’s recommendations, the Cuban ambassador to China conducted an on-the-spot investigation and expressed his appreciation of the plant’s products. Besides Cuba, the plant’s products also enjoy a high reputation among customers in Pakistan, Chile, Australia, Papua New Guinea, Ghana and Southeast Asia. Zhangjiakou had its

A New Method for Forecasting the Life Test Data of Mechanical Products

The model for forecasting the test data on mechanical products is established in the application of the grey system theories. A new formula of the background value is introduced into the model. The result of an example shows the method can reduce test expense and enhance the precision of forecasting.

China's Processing Trade Development for Mechanical and Electrical Products

Since the launch of the economic reform and opening to the outside world, China has seen rapid growth in its export of mechanical and electrical products, with its export

Seize the Opportunity and Make Efforts to Increase Zhejiang's Export of Mechanical and Electrical Products

Zhejiang’s machine-building industryhas made sustained efforts to increase itsexports through the combination ofindustry and trade. In the past decade,Zhejiang’s export volume of mechanicaland electrical products has increased over 10times, becoming the leading exports fromthe province. Zhejiang has thereforebecome an important province exportingmachinery in China.

Measures for Administration of the Import of Mechanical and Electronic Products

The Measures for the Administration of the Import of Mechanical and Electronic' Products co-formulated by the Ministry of Commerce,the General Administration of Customs and the General Administration of Quality Supervision,Inspection and Quarantine,was hereby promul- gated,which entered into force as of May 1,2008.

A New Elastoplastic 3D Sand Production Model for Fractured Gas Fields

Reservoirs characterized by high temperature,high-pressure,medium high cementation strength,low porosity,and low permeability,in general,are not affected by sand production issues.Since 2009,however,it is known that cases exists where sand is present and may represent a significant technical problem(e.g.,the the Dina II condensate gas field).In the present study,the main factors affecting sand production in this type of reservoir are considered(mechanical properties,stress fields,production system,completion method and gas flow pattern changes during the production process).On this basis,a new liquid-solid coupled porous elasto-plastic 3D sand production model is introduced and validated through comparison with effective sand production data.The related prediction errors are found to be within 15%,which represents the necessary prerequisite for the utilization of such a model for the elaboration of sand prevention measures.

Factors Influencing Price of Agricultural Products and Stability Countermeasures

Factors leading to rise of prices of agricultural products mainly include tension of supply-demand relationship,promotion of production cost and circulation cost,and speculation of Refugee Capital(Hot Money).Factors leading to low price and difficult sales of agricultural products mainly include asymmetry of supply-demand information,lack of risk management tools for prices of agricultural products and decentralized and small-scaled operation of farmers.On the basis of these factors,this paper presents following countermeasures and suggestions for stabilizing prices of agricultural products:firstly,building long-effect mechanism for production and sales of agricultural products;secondly,expand the production and increase supply of agricultural products;thirdly,control the rising range of production cost for agricultural products;fourthly,enhance organization level of farmers;fifthly,promote innovation and development of risk management tools for prices of agricultural products.

A Critical Review on Superchilling Preservation Technology in Aquatic Product

aquatic product, known as one of the good resources for white meat, has been widely accepted by the consumers due to its high protein, low fat, especially low cholesterol. With the fast development of living standards around the world, the consumer demands for high quality, nutrition, safety and freshness of ifshery food are increasing. Thus, high efifcient preservation technologies for aquatic products become particularly important. Superchilling is one of the controlled-temperature preservation technologies for seafood. Aquatic products can be kept in better quality under superchilling conditions. This review introduced the principle and development of superchilling process, mainly focusing on research progresses and technical dififculties of superchilling. The growth mechanism of ice crystals and the feasibility of application of computational lfuid dynamics in analyzing the temperatures variation and ice crystals during superchilling progress were also discussed, which will provide theoretical foundation for its improvement and application.

Breeding of Yuetang 08776,a New Sugarcane Variety Suitable for Mechanized Production

[Objectives]To study the breeding of a new sugarcane variety Yuetang 08776 suitable for mechanized production.[Methods]With Yuetang 96-86 as the female parent and Yuetang 99-66 as the male parent,Yuetang 08776 was bred by the Bioengineering Institute of Guangdong Academy of Sciences.It was approved as a non-major crop variety by the Ministry of Agriculture and Rural Affairs in December,2019.Through many years of multi-pilot trials,the characters,traits and disease resistance of Yuetang 08776 were investigated,and the key points of its cultivation technique were summarized.[Results]Yuetang 08776 is characterized by medium maturity,high sugar content,high and stable yield,strong cold and drought resistance,large number of effective stems,strong ratooning ability and lodging resistance.Yuetang 08776 has excellent agronomic traits,and has been identified as moderately resistant to smut and mosaic disease.The average cane yield of Yuetang 08776 was 119.89 t/ha,18.50 t/ha higher than that of CK,an increase of 18.25%.The average sugar yield was 17.15,2.11 t/ha higher than that of CK,an increase of 14.03%.The average sucrose content of Yuetang 08776 in the early period(November to December)was 13.20%,0.71 percentage points lower than that of CK;in the middle and late period(January to March of the following year),the average sucrose content was 15.23%,0.22 percentage points lower than that of CK;and the average sucrose content of the whole period was 14.21%,0.47 percentage points lower than that of CK.[Conclusions]Yuetang 08776 is a sugarcane variety with medium maturity,high sugar,high and stable yield,strong resistance and good ratooning.It is suitable for mechanized seeding,management and harvesting,and suitable for planting and popularizing in most sugarcane production areas of Guangdong,Guangxi and Yunnan.

Effect and Analysis of Mechanized Production on Ratooning Ability of Guitang 47

[Objectives] This study was conducted to explore the effect of machine harvesting on ratooning ability of Guitang 47, and to provide basis for mechanized production of Guitang 47. [Methods] On the basis of mechanized planting and management of newly planted sugarcane Guitang 47, a comparative test of machine harvesting and manual harvesting was conducted, during which the plant generation rate, sugarcane yield, sucrose content and related agronomic traits of ratoon cane were continuously investigated in two years after machine harvesting of the newly planted sugarcane. [Results] There were no significant differences in the plant generation rate, plant height, stalk diameter, millable cane, sugarcane yield and sucrose content from manual harvesting of Guitang 47 in the first and second years after machine harvesting. In the second year after machine harvesting, the yields of ratoon cane and the sugar content reached 101.70 and 15.32 t/hm^2, respectively, which were equivalent to those of manual harvesting. [Conclusions] Guitang 47 has strong ratooning ability and lodging resistance and strong resistance to rolling and crushing, and is adaptive to full mechanized production. It should be promoted and accelerated in sugarcane areas lacking labor to reduce costs and increase benefits.

Intrinsic product polarization and branch ratio in the S（~1D,~3P）＋HD reaction on three electronic states

The intrinsic product polarization and intramolecular isotope effect of the S（~1D,~3P） ＋ HD reaction have been investigated on both the lowest singlet state（1A） and the triplet state（3A and 3A） potential energy surfaces by using quasi-classical trajectory and quantum mechanical methods.The calculations indicate that intramolecular isotope effects are different on the three electronic states.The stereodynamics study shows that the P（θr） distributions,P（φ r） distributions,and polarization-dependent differential cross sections（PDDCSs）（00） are sensitive to mass factor and the product angular momentum vectors are not only aligned but also oriented.

Applying Technique Assembly to Raise the Production Level of Mechanized Agriculture

On the basis of accomplishment obtained in the course of mechanized crop production owing to the progress of science and technology,the authors propose further in this paper the target and prineiples of technique assembly in agricultural production.A typical high yield model of technique assembly for soybean and wheat production is given as an example.

Key theoretical and technical issues and countermeasures for effective development of Gulong shale oil, Daqing Oilfield, NE China

Aiming at the four issues of underground storage state,exploitation mechanism,crude oil flow and efficient recovery,the key theoretical and technical issues and countermeasures for effective development of Gulong shale oil are put forward.Through key exploration and research on fluid occurrence,fluid phase change,exploitation mechanism,oil start-up mechanism,flow regime/pattern,exploitation mode and enhanced oil recovery(EOR)of shale reservoirs with different storage spaces,multi-scale occurrence states of shale oil and phase behavior of fluid in nano confined space were provided,the multi-phase,multi-scale flow mode and production mechanism with hydraulic fracture-shale bedding fracture-matrix infiltration as the core was clarified,and a multi-scale flow mathematical model and recoverable reserves evaluation method were preliminarily established.The feasibility of development mode with early energy replenishment and recovery factor of 3o%was discussed.Based on these,the researches of key theories and technologies for effective development of Gulong shale oil are proposed to focus on:(1)in-situ sampling and non-destructive testing of core and fluid;(2)high-temperature,high-pressure,nano-scale laboratory simulation experiment;(3)fusion of multi-scale multi-flow regime numerical simulation technology and large-scale application software;(4)waterless(CO_(2))fracturing technique and the fracturing technique for increasing the vertical fracture height;(5)early energy replenishment to enhance oil recovery;(6)lifecycle technical and economic evaluation.Moreover,a series of exploitation tests should be performed on site as soon as possible to verify the theoretical understanding,optimize the exploitation mode,form supporting technologies,and provide a generalizable development model,thereby supporting and guiding the effective development and production of Gulong shale oil.

Effect Analysis of "One Prevention Double Reduction" of Aerial Control in Corn Fields in Daiyue District, Tai’an City

The main technical content of full mechanized corn production in Daiyue District is explained,and the problems of disease and insect pest control in the middle and late growth stage of corn in full mechanized production are analyzed."One prevention double reduction"of corn performed by unmanned aerial vehicle(UAV)and self-propelled sprayer is compared and analyzed,and some suggestions are put forward for further popularization and application of full mechanized corn production.

Gut Microbiota Brings a Novel Way to Illuminate Mechanisms of Natural Products in vivo

Poor bioavailability and undefined major/direct targets are two major obstacles for herbal medicines and natural products（NPs） to elucidate their precise mechanisms in vivo. Gut microbiota is an important bridge between eukayotic body and environment, which can interact with a majority of medicines with poor bioavailability and mediate their in vivo pharmacological activities. There are two main modes through which gut microbiota may mediate the pharmacological effects of NPs. First, gut microbiota catabolizes the NPs in herbal medicines into secondary metabolites with higher bioavialability and/or higher activity, facilitating the NPs enter circulation and exert beneficial impact at the pathological spot. Second, herbal medicines and NPs can favorably shift the compositional structure of gut microbiota, thereby performing remote functions to diseased organs/tissues via the systemic impaction of gut microbiota. In this review, the potential pathways were summarized through which gut microbes facilitate the pharmacological functions of herbal medicines and NPs and highlight the significance of gut microbiota in clarifying the in vivo mechanisms of herbal medicines and NPs.

Interior noise field of a viscoelastic cylindrical shell excited by TBL pressure fluctuations:Ⅰ.Production mechanisms of the noise

Applying the wavenumber frequency transfer function to describe the whole system including tht elastic cylindrical shell and the fluid loading, a general expression of the cross spectrum of the interior noise induced by the TBL (turbulent boundary layer) pressure fiuctuations is derived. There are two production mechanisms of the noise: one is direct transfer of the convective ridge of the pressure fluctuations through the shell, the other is the reradiation of resonance modes excited by the pressure fluctuations. At low frequencies the noise produced by the latter mechanism is dominant. Solving the frequency equation of the cylindrical shell with liquid loading, the two Stoneley-type poles in the complex K plane are presented. They are the major sources of the reradiation of shell at low frequencies. Finally, effects of the shell radius, shell thickness, absorption of material and the flow speeds on the noise reduction are computed by numerical iniegration.

The original mechanism of vari-toned song production in mingming cicada(Oncotympana maculaticollis Motsch)

In this paper, the original process of vari-toned song in the Mmgming cicada is revealed, and the brand-new recognition for studies of the song mechanism in cicadas is opened up. Each vari-toned syllable 'Weiying' is composed of 'Wei' with the basic sound (BS) as the dominant tone and 'ying' with the upper partials (UP2) as the dominant tone, and the upper partials (UP1) is a sound accompaniment of low intensity.The BS, UP1 and UP2 are produced by vibrations of the long ribs LR2,3 and LR1 in sounding membrane driven, separately, by two kinds of the twich in sounding muscle, 'Wei' and 'ying' are separately produced by the prin-subordinate vibrations of LR2,3 -LR1 and LR1-LR2,3. The LR1 and LR2,3 are analogous to a string tensioned two ends and a beam hinged two ends with a load in the middle respectively. Obtained the acoustic properties of sounding vibration are not only suited to the structural characteristics of LR1, 2, 3 but also consist basically with the acoustic properties of song.

N2O emission in partial nitritation-anammox process

Nitrous oxide(N2O)is one of the significant greenhouse gases,and partial nitritation-anammox(PNA)process emits higher N2O than traditional nitrogen removal processes.N2O production in PNA mainly occurs in three different pathways,i.e.,the ammonia oxidizing bacteria(AOB)denitrification,the hydroxylamine(NH2 OH)oxidation and heterotrophic denitrifiers denitrification.N2O emission data vary significantly because of the different operational conditions,bioreactor configurations,monitoring systems and quantitative methods.Under the common operational parameter scopes of PNA,N2O emission via NH2 OH oxidation dominates at relatively low dissolved oxygen(DO),low inorganic carbon(IC),high pH or low N02-concentration,while N2O emission via AOB denitrification dominates at relative higher DO,higher IC.lower pH or higher N2O-concentration.AOB are highly enriched while nitriteoxidizing bacteria(NOB)are rarely found in partial nitritation process,and the order Nitrosomonadales of AOB is the dominant group and N2O producer.Anammox bacteria,AOB and certain amount of heterotrophic denitrifying bacteria are observed in the anammox process,the genus Denitratisoma and the heterotrophic denitrifying bacteria in the deep layer of anammox granules are the dominant N2O generation bacteria.In one-stage PNA reactors,anammox bacteria account for a large fraction of the biomass,AOB account for small portion,and NOB account for even less.The microbial community,diversity and N2O producers in one-stage PNA reactors are similar with those in two-stage PNA reactors.The dominant anammox bacteria,AOB and NOB in PNA are the species Candidatus Brocadia,the genera of Nitrotoga,Nitrospira and Nitrobacter,and the genus Nitrosomonas,respectively.The relations between N2O emission pathways and microbial communities need further study in the future.

A NUMERICAL STUDY ON MECHANISM OF S-STARTS OF NORTHERN PIKE (ESOX LUCIUS)

Northern pike is regarded as a specialist in swimming acceleration. The force production mechanism of northern pike, Esox lucius, during its predation S-starts was numerically studied in this article. The problem was reasonably simplified to a loose-coupling problem of fish swimming dynamics and hydrodynamics just in the swimming direction. The approach involved the simulation of the flow by solving the two-dimensional unsteady incompressible Navier-Stokes equations and decribing the fish motion dynamics based on Newton＇s Second Law. Visualizations of flow fields and vortex structures were performed. The results show that the large acceleration is obtained mainly in the first undulatory cycle in which the amplitude increases. In the second cycle, a couple of vortices are generated and induce a jet. In the third cycle, the jet is strengthened by the mergence of the vortices in the same direction. Through discussing the effects of various controllable factors on the swimming performance, it is found that the actual locomotion mode of the northern pike in nature is just the best choice.