DEM Simulation of Clod Crushing by Bionic Bulldozing Plate

Through evolving over millions of years, earthworm has developed the typical wavy body surface. The non-smooth surface shape can break the clods into small pieces, which is one of the important reasons to make earthworm move freely in soil. Based on engineering bionics, the non-smooth body surface of earthworm was regarded as the bionic prototype, and a bionic wavy plane bulldozing plate was designed. In order to analyze the clod crushing mechanism by the bionic bulldozing plate, the nonlinear mechanical model of contact between soil particles was established and the clod-crushing processes by the bionic bulldozing plate and the smooth bulldozing plate were simulated by Distinct Element Method (DEM). Simulation results indicate that the bionic bulldozing plate has stronger clod-crushing ability and can break much more clods than the smooth bulldozing plate can.     

Design Principles of the Non-smooth Surface of Bionic Plow Moldboard

1　IntroductionTransferringbiologyfunctiontoengineeringtech nology[1] isaprominentprogressintechnologicalfields ,whichenrichesthecontentofTRIZsystematicmethod .Thenon smoothsurfacesofthetypicalsoilan imalshavetheeffectsofreducingsoiladhesion ,whichhasbeenconvincedandgraduallyaccepted .Thebionicplowmoldboardisanappliedexampleofimitatingthecharacteristicsofsoilanimals’surfaceappearancesandpracticingtheBionicTheoryofNon SmoothSurface(TNSS) .ThebasisofTNSSisnon smoothsurfaceef fects[2 ,3] …     

Mechanical Properties and Microstructure of Bionic Non-Smooth Stainless Steel Surface by Laser Multiple Processing

Laser multiple processing, i.e. laser surface texturing and then Laser Shock Processing (LSP), is a new surface processingtechnology for the preparation of bionic non-smooth surfaces. Based on engineering bionics, samples of bionic non-smoothsurfaces of stainless steel 0Crl 8Ni9 were manufactured in the form of reseau structure by laser multiple processing. The mechanicalproperties (including microhardness, residual stress, surface roughness) and microstructure of the samples treated bylaser multiple processing were compared with those of the samples without LSP The results show that the mechanical propertiesof these samples by laser multiple processing were clearly improved in comparison with those of the samples without LSP Themechanisms underlying the improved surface microhardness and surface residual stress were analyzed, and the relations betweenhardness, comnressive residual stress and roughness were also presented.     

The Mechanism of Drag Reduction around Bodies of Revolution Using Bionic Non-Smooth Surfaces

Bionic non-smooth surfaces （BNSS） can reduce drag. Much attention has been paid to the mechanism of shear stress reduction by riblets. The mechanism of pressure force reduction by bionic non-smooth surfaces on bodies of revolution has not been well investigated. In this work CFD simulation has revealed the mechanism of drag reduction by BNSS, which may work in three ways. First, BNSS on bodies of revolution may lower the surface velocity of the medium, which prevents the sudden speed up of air on the cross section. So the bottom pressure of the model would not be disturbed sharply, resulting in less energy loss and drag reduction. Second, the magnitude of vorticity induced by the bionic model becomes smaller because, due to the sculpturing, the growth of tiny air bubbles is avoided. Thus the large moment of inertia induced by large air bubble is reduced. The reduction of the vorticity could reduce the dissipation of the eddy. So the pressure force could also be reduced. Third, the thickness of the momentum layer on the model becomes less which, according to the relationship between the drag coefficient and the momentum thickness, reduces drag.     

Insecticide-treated plastic tarpaulins for control of malaria vectors in refugee camps

Spraying of canvas tents with residual pyrethroid insecticide is an established method of malaria vector control in tented refugee camps. In recent years, plastic sheeting (polythene tarpaulins) has replaced canvas as the utilitarian shelter material for displaced populations in complex emergencies. Advances in technology enable polythene sheeting to be impregnated with pyrethroid during manufacture. The efficacy of such material against mosquitoes when erected as shelters under typical refugee camp conditions is unknown. Tests were undertaken with free-flying mosquitoes on entomological study platforms in an Afghan refugee camp to compare the insecticidal efficacy of plastic tarpaulin sprayed with deltamethrin on its inner surface (target dose 30 mg/m2), tarpaulin impregnated with deltamethrin (initially > or = 30 mg/m2) during manufacture, and a tent made from the factory impregnated tarpaulin material. Preliminary tests done in the laboratory with Anopheles stephensi Liston (Diptera: Culicidae) showed that 1-min exposure to factory-impregnated tarpaulins would give 100% mortality even after outdoor weathering in a temperate climate for 12 weeks. Outdoor platform tests with the erected materials (baited with human subjects) produced mosquito mortality rates between 86-100% for sprayed or factory-impregnated tarpaulins and tents (average approximately 40 anophelines and approximately 200 culicines/per platform/night), whereas control mortality (with untreated tarpaulin) was no more than 5%. Fewer than 20% of mosquitoes blood-fed on human subjects under either insecticide-treated or non-treated shelters. The tarpaulin shelter was a poor barrier to host-seeking mosquitoes and treatment with insecticide did not reduce the proportion blood-feeding. Even so, the deployment of insecticide-impregnated tarpaulins in refugee camps, if used by the majority of refugees, has the potential to control malaria by killing high proportions of mosquitoes and so reducing the average life expectancy of vectors (greatly reducing vectorial capacity), rather than by directly protecting refugees from mosquito bites. Mass coverage with deltamethrin-sprayed or impregnated tarpaulins or tents has strong potential for preventing malaria in displaced populations affected by conflict.     

The Wear-Resistance of 3Cr2W8V Steel with Cave Pit Non-Smooth Surface Processed by Laser

The cave pit non-smooth surface on the 3Cr2W8V die steel were processed by laser and the size and microstructure of the non-smooth units were studied. The wear-resistance and hardness of the 3Cr2W8V steel with non-smooth surface were measured. The results show that the wear-resistance characteristic is better if the distance between non-smooth units is smaller. The size (the depth, the width), the hardness and the microstructure of the units vary with the laser parameters. When the current intensity and the pulse duration increase, the microstructure of non-smooth unit becomes coarser for the increase in the width and volume, as a result, the hardness decreases and the wear-resistance improves. The wear-resistance of the non-smooth material under higher current intensity and longer pulse duration was found to be better in the experiments. The improved degree of wear-resistance lies in the combination of size, microstructure and hardness of non-smooth unit.     

Bionic Leaf Simulating the Thermal Effect of Natural Leaf Transpiration

We proposed a kind of bionic leaf to simulate the thermal effect of leaf transpiration. The bionic leaf was firstly designed to be composed of a green coating, a water holding layer, a Composite Adsorbent （CS） layer and an adsorption-desorption rate controlling layer. A thermophysical model was established for the bionic leaf, and the dynamic simulation results reveal that the water holding layer is not necessary; a CS of high thermal conductivity should be selected as the CS layer; the adsorp- tion-desorption rate controlling layer could be removed due to the low adsorption-desorption rate of the CS; and when CaC12 mass fraction of the CS reaches 40%; the bionic leaf could simulate the dynamic thermal behavior of the natural leaf. Based on the simulation results, we prepared bionic leaves with different CaC12 content. The thermographies of the bionic leaf and the natural leaf were shot using the Infrared Thermal Imager. The measured average radiative temperature difference between the bionic and natural leaves is less than 1.0 ℃.     

Bionic Composite Material Simulating the Optical Spectra of Plant Leaves

Though many physical models have been proposed to simulate the spectra of plant leaves, there are few reports on the material simulation of plant leaves. In order to prepare a material that could simulate the reflectance spectra of plant leaves, the spectral reflectance characteristics of plant leaves and their forming mechanism were analyzed. The study indicated that the reflectance spectra of plant leaves exhibits four common characteristics, which were determined by the spongy inner structure and biochemical contents (chlorophyll, water) of plant leaves. In our procedure, the chlorophyll was concealed into the high-oxygen-barrier polyvinyl alcohol (PVA) film to improve its photostability, and the water was sealed into the bag of high-vapor-barrier polyvinylidene chloride (PVDC) to prevent its vaporization loss. Subsequently, taking the structures of plant leaves and petals as simulating models and considering the limits of PVA film and PVDC bag, a novel bionic composite material constituted with three layers was designed and prepared. The spectral tests and endurance experiment show that the bionic composite material exhibits almost the same reflectance spectrum with those of green leaves, and its spectrum changes little after sunlight treatment for three months, which proves a good sunlight endurance of this bionic composite material.     

A Biological Coupling Extension Model and Coupling Element Identification

Extenics is a newly developed interdisciplinary subject combining mathematics, philosophy and engineering. It providesuseful formalized qualitative tools and quantitative tools for solving contradictory problems. In this paper, extension theory isintroduced briefly and the primary applications of this theory and methods in bionic engineering research are discussed. Theextension model of biological coupling functional system is established. In order to identify the primary and secondary sequencingof coupling elements, the Extension Analytic Hierarchy Process (EAHP) was adopted to analyze the contribution ofeach coupling element to the coupling functional system. Thus, the influence weight factor of each coupling element can bedetermined, so as to provide a new approach for solving primary and secondary sequencing problem of coupling elements in aquantitative way, and facilitate the subsequent bionic coupling study.     

D.D.T. Impregnation of Sacks for the Protection of Stored Cereals Against Insect Infestation

Cotton flour sacks, jute flour sacks, jute bran sacks and jute grain sacks have been impregnated with 1 and 5 % by weight of D.D.T. Treated and untreated sacks, each containing 1 cwt. of a mixture of grain (5 parts) and weatings (1 part), were exposed to severe infestation by adults of Calandra granaria, Tribolium castaneum, Ptinus tectus, Oryzaephilus surina-mensis and Ephestia elutella . After storage for 15 weeks at a mean temperature of 21.3 C. and a mean relative humidity of 65 %, the numbers of adult insects in each sack were determined by sieving the contents.
The results with Ephestia elutella were inconclusive. The results with the four species of beetles showed that the eventual degree of infestation of the contents of the sacks was dependent upon the closeness of weave and the D.D.T. content of the sacking material. Impregnation of sacking with 1 % of D.D.T. should afford adequate protection against insect infestation to clean bagged goods stored in stowages which are not heavily infested. Impregnation with 5 % of D.D.T. should offer a very high degree of protection at all times and can almost entirely prevent infestation, if the treated material is of sufficiently close weave to afford some mechanical hindrance to penetration by insects.     

Study on Mechanics of Driving Drum with Superelastic Convexity Surface Covering-Layer Structure

Belt conveyor is one of the main transport equipment in coal mine and the driving drum is its key part. With the method of bionic design, the mushroom morphological structure is applied to the design of covering-layer structure of driving drum surface of belt conveyor. Superelastic rubber with large deformation is adopted as the covering-layer material. Nonlinear constitutive model of rubber, which is of superelasticity and large deformation, is established. The stress states and deformation principles of driving drums including both bionic covering-layer and common covering-layer are obtained by static intensity analysis with Finite Element Analysis (FEA) software ANSYS. The values of the stress and strain on the driving drum surface are gotten and the dangerous area is determined. FEA results show that the superelastic convexity surface structure can enlarge the contact area between the driving drum and viscoelastic belt. The results also show that in comparison with common driving drum, the bionic surface driving drum can not only increase the friction coefficient between drum and belt but also prolong its service life.     

Biology Coupling Characteristics of Mole Crickets' Soil-Engaging Components

Mole cricket (Gryllotalpa orientalis) is a typical animal living under ground. The soil-engaging components of mole cricket have the capacity of wear resistance against soil. In this paper, the foreleg, tergum and forewing of mole cricket were chosen as soil-engaging components and were observed by stereomicroscope (SM), Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM). The functions of the components were analyzed from the viewpoints of both entomology and bionics. The factors for function realization were found, and the single effect and coupling effect of these factors were investigated. Results show that the wear resistance characteristic of mole cricket is realized by biology coupling. The research of biology coupling provides a foundation to the technology of bionic coupling.     

Network organization of interstitial connective tissue cells in the human endolymphatic duct.

The human endolymphatic duct (ED) and sac of the inner ear have been suggested to control endolymph volume and pressure. However, the physiological mechanisms for these processes remain obscure. We investigated the organization of the periductal interstitial connective tissue cells and extracellular matrix (ECM) in four freshly fixed human EDs by transmission electron microscopy and by immunohistochemistry. The unique surgical material allowed a greatly improved structural and epitopic preservation of tissue. Periductal connective tissue cells formed frequent intercellular contacts and focally occurring electron-dense contacts to ECM structures, creating a complex tissue network. The connective tissue cells also formed contacts with the basal lamina of the ED epithelium and the bone matrix, connecting the ED with the surrounding bone of the vestibular aqueduct. The interstitial connective tissue cells were non-endothelial and non-smooth muscle fibroblastoid cells. We suggest that the ED tissue network forms a functional mechanical entity that takes part in the control of inner ear fluid pressure and endolymph resorption.     

The Lightweight Design of Low RCS Pylon Based on Structural Bionics

<正> A concept of Specific Structure Efficiency (SSE) was proposed that can be used in the lightweight effect evaluation ofstructures.The main procedures of bionic structure design were introduced systematically.The parameter relationship betweenhollow stem of plant and the minimum weight was deduced in detail.In order to improve SSE of pylons, the structural characteristicsof hollow stem were investigated and extracted.Bionic pylon was designed based on analogous biological structuralcharacteristics.Using finite element method based simulation, the displacements and stresses in the bionic pylon were comparedwith those of the conventional pylon.Results show that the SSE of bionic pylon is improved obviously.Static, dynamic andelectromagnetism tests were carried out on conventional and bionic pylons.The weight, stress, displacement and Radar CrossSection (RCS) of both pylons were measured.Experimental results illustrate that the SSE of bionic pylon is markedly improvedthat specific strength efficiency and specific stiffness efficiency of bionic pylon are increased by 52.9% and 43.6% respectively.The RCS of bionic pylon is reduced significantly.     

Study on some alkoxysilanes used for hydrophobation and protection of wood against decay

Two types of silanes, namely aklylalkoxysilanes and arylalkoxysilanes, were used for wood impregnation aiming at hydrophobisation of the ligno-cellulose material. The suggested mixture of alkyltriethoxysilanes and dialkyldiethoxysilanes improved water repellence when compared to conventionally used silanes. An attempt to immobilise boric acid with the siloxane matrix was also done. Decay resistance of the treated samples was tested by soil-jar test using the brown rot fungus Postia placenta.Features of the impregnated wood such as moisture content, swelling, anti-swelling efficacy and weight percentage gain were not significantly related to the mass loss of samples caused by the fungus. Samples impregnated with EtPhSi(OEt)₂ silanes showed improved durability (3.5–11.5% mass loss). Addition of boric acid to two of the silanols showed the best result for durability of wood, i.e. the lowest mass loss of 2.3 and 1.1%. These treatments upgraded the wood to “very durable”, a significant improvement from its natural status, i.e. slightly durable. The studied alkoxysilanes have moderate ability to penetrate the wood cell wall and hence to improve its hydrophobicity. These silanes are promising although more research should be carried out on the degree of oligomer polymerisation in the wood cell wall.     

Steroid bioconversion in water-insoluble organic solvents: Δ1-Dehydrogenation by free microbial cells and by cells entrapped in hydrophilic or lipophilic gels

A cell suspension in a water-insoluble organic solvent (benzene: n-heptane, 1 : 1 by volume) of Nocardia rhodocrous (previously induced to synthesize steroid Δ¹dehydrogenase) rapidly catalyzed the stoichiometric oxidation of 4-androstene-3,17-dione (4-AD) to androst-l,4-diene-3,17-dione (ADD) in the presence of phenazine methosulfate (PMS). High levels of 4-AD or PMS reduced the conversion rates. No appreciable decrease in the conversion rate was observed on adding aqueous buffer solution to the thawed ceils (up to 9.4 g water/g dry cell). The whole cells were immobilized by entrapment in a hydrophilic gel (H-gel) or a lipophilic gel (L-gel) by use of a water-soluble or water-insoluble photocrosslinkable prepolymer. The reticula of H- and L-gel matrices were impregnated with water and organic solvent, respectively. Both the H- and L-gels could convert 4-AD to ADD in the presence of PMS, the L-gel showing a slightly higher conversion rate. Various lines of evidence indicate that the limiting factor is the penetration rate of 4-AD into gel particles for the H-gel, and the penetration rate of PMS for the L-gel. The catalytic activities decreased considerably after several successive runs with the free cell suspension system, while the immobilized cells were more stable, the stability of H-gel and L-gel being almost the same.     

Tangent Resistance of Soil on Moldboard and the Mechanism of Resistance Reduction of Bionic Moldboard

The tangent resistance on the interface of the soil-moldboard is an important component of the resistance to moving soil . We developed simplified mechanical models to analyze this resistance. We found that it is composed of two components, the frictional and adhesive resistances. These two components originate from the soil pore, which induced a capillary suction effect, and the soil-moldboard contact area produced tangent adhesive resistance. These two components varied differently with soil moisture. Thus we predicted that resistance reduction against soil exerted on the non-smooth bionic moldboard is mainly due to the elimination of capillary suction and the reduction of physical-chemical adsorption of soil.     

Prefabricated vascularized bone flap: a tissue transformation technique for bone reconstruction

In this study, an attempt was made to transform a muscle vascularized pedicle raised on host vessels into a vascularized bone flap, using recombinant human bone morphogenetic protein 2 (rhBMP-2). The purpose of this study was to produce new bone vascularized in nature to increase the survival rate of the subsequently grafted bone and to fabricate the newly formed bone into the desired shape. Silicone molds in the shape of a rat mandible were used to deliver rat bone matrix impregnated with or without rhBMP-2. A muscle pedicle the same size as the mold was raised on the saphenous vessels in the rat thigh and then sandwiched in the center of the silicone molds. The molds were sliced in half and each section was filled with rat bone matrix that was impregnated either with 25 microg of rhBMP-2 for the experimental group or with diluting material alone for the control group. The sandwiched flaps were then secured by tying them to the adjacent muscles and were harvested at 2 and 4 weeks after surgery. Three and six rats were used in the control and experimental groups at each time point, respectively. Bone formation was assessed in the ex vivo specimens by macroscopic, radiologic, and histologic evaluation. Macroscopically, the continuation of the vascular pedicle was clearly visible for both the control and experimental muscle flaps. However, no evidence of muscle-tissue transformation was observed in the control flaps, whereas all the flaps treated with rhBMP-2 produced new bone that replicated the shape of the mold exactly and had saphenous vessels supplying the newly formed bone. This study demonstrates that this experimental model has the potential to be therapeutically applied for effective bone reconstruction.     

Schistosoma mansoni: production of cercarial eicosanoids as correlates of penetration and transformation

A method was developed, using a 0.25% agar matrix, to incorporate varying concentrations of linoleate and correlate cercarial transformation and eicosanoid production in vitro. Schistosoma mansoni cercariae were stimulated to penetrate over a wide range of linoleate concentrations; however, the transformation process occurred over a narrow range. Approximately 25% of cercariae penetrated the agar matrix in controls (no linoleate) and 0.003 mM linoleate. Penetration rates rose gradually until, at linoleate concentrations of 0.3 mM or greater, penetration approached 100%. The transformation process did not begin until the linoleate concentration in agar reached 2.0 mM (3.8%), and achieved maximum (91%) at 3.0 mM. A concentration of 9.0 mM linoleate gave 100% penetration and transformation rates, but penetration was superficial and cercariae were not viable. Cercarial eicosanoid production was concentration-related. Various eicosanoid classes were associated with cercarial penetration and transformation. Penetration rates were correlated with increasing leukotriene (LT, R = 0.9541) and hydroxyeicosatetraenoic acid (HETE, R = 0.8363) levels, while transformation rates correlated with increasing prostaglandin levels (R = 0.9225). Correlating eicosanoid production with penetration and transformation rates strengthened the hypothesis that successful cercarial penetration and transformation are dependent on both skin essential fatty acid levels and resulting cercarial eicosanoid production.     

Lambing rates and litter size following carazolol administration prior to insemination in Kivircik ewes

The effect of carazolol on the ease of penetrating the cervix during artificial insemination, lambing rate and litter size was studied using 1.5–4.0-year old Kivircik ewes in an incomplete 3 × 2 × 2 experimental design. All of the ewes in this study were synchronized for oestrus by insertion of a progesterone impregnated vaginal sponge for 12 days and administration of 400 IU PMSG at sponge withdrawal. Three methods of service were compared: natural service, artificial insemination (AI) with fresh semen, or AI with frozen semen. Two times of insemination (fixed time AI versus AI at observed oestrus) were compared on the fresh and frozen AI treatments. The absence (control) or use of carazolol (carazolol; 0.5 mg/ewe i.m. 30 min before mating) was the third factor in the design and penetration of the cervix by the insemination pipette was assessed as shallow (<10 mm), middle (10–20 mm) or deep (>20 mm). Natural service ewes were only mated at observed oestrus. Consequently, the factorial design was incomplete and there were a total of 10 treatments each represented by 30 ewes. Natural service resulted in a significantly (P < 0.05) higher lambing rate and litter size (86%; 2.0 ± 0.05 lambs/ewe) than AI using fresh (65%; 1.6 ± 0.1 lambs/ewe) or frozen (40%; 1.4 ± 0.14 lambs/ewe) semen. For AI animals the lambing rate and litter size were not significantly different when service was at a fixed time (50%; 1.5 ± 0.12 lambs/ewe) or at observed oestrus (56%; 1.5 ± 0.12 lambs/ewe). Carazolol did not permit complete cervical penetration in any ewe. Deep penetration of the cervix at AI was achieved in 33% of untreated (control) and 48% of carazolol treated ewes (P < 0.05). However, the proportion of ewes in which penetration of the cervix and semen deposition was greater than shallow was similar for control (82%) and carazolol (85%), and lambing rate and litter size were similar for both treatments. Over the three service methods, the lambing rate was 56% for control and 63% for carazolol (NS) and litter size was similar for both treatments. It was concluded that the carazolol treatment used prior to natural mating or AI in this experiment did not improve lambing rate or litter size in Kivircik ewes.