Influence of the Extraction Process on the Characteristics of Romanian Mountain Walnut Oil

The objective of this work is to extract walnut oil using various processes in order to compare the influence on the nature of the components extracted, and thus identify the areas of potential use. We carried out the extractions by mechanical process, thanks to a press in reduced model provided with a worm. We obtained cold extracted oil whose characteristics slightly diverge from extra virgin oil found in shops in Romania, but its composition is similar. We were also able to extract by chemical process using two methods, Folch and Soxhlet. Commercially available table walnut oils are only cold extracted to avoid the presence of solvents. Those are difficult to remove and strongly oxidize the oil. Currently, consumers appreciate walnut oil for its taste and nutritional qualities. In nutrition, this oil is put forward for its composition rich in polyunsaturated fatty acids, which are needed for human body. Food supplements made from walnut oil are available today. For the moment, this is the only use of walnut oil. Indeed, there are some studies on other fields of application, but they remain in the field of research and nothing has yet been commercialized. In this present study, we compared the chemical and physical properties of cold-extracted oil with the solvent extraction of walnut kernel originating from the mountain region of Rumania. The cold extracted oil has a high content of polyunsaturated fatty acids (63%) and monounsaturated fatty acids (30%), a very low level of saturated fatty acid (7%) and no content of linolenic acid. The Soxhlet and Folch methods produced slightly different oils with increased amounts of minor components, which changes their characteristic. Even when solvent-extracted oils do not meet the standard criteria imposed by the Codex Alimentarius, they offer a possible use in the fields of food, cosmetics industries and biomedicine.

JrATHB-12 mediates JrMYB113 and JrMYB27 to control the anthocyanin levels in different types of red walnut

Red walnut has broad market prospects because it is richer in anthocyanins than ordinary walnut.However,the mechanism driving anthocyanin biosynthesis in red walnut is still unknown.We studied two types of red walnut,called red walnut 1(R1),with a red pericarp and seed coat,and red walnut 2(R2),with a red seed coat only.R1 mostly contained cyanidin-3-O-galactoside,while R2 contained a various amounts of cyanidin-3-Ogalactoside,cyanidin-3-O-arabinoside,and cyanidin-3-O-glucoside.The LDOX-2(LOC109007163)and LDOX-3(LOC109010746)genes,which encode leucoanthocyanidin dioxygenase/anthocyanidin synthase(LDOX/ANS),were preliminarily indicated as the crucial genes for anthocyanin biosynthesis in R1 and R2,respectively.The MYB differential genes analysis showed that MYB27 and MYB113 are specifically expressed in the red parts of R1 and R2,respectively,and they are regarded as candidate regulatory genes.Ectopic expression in Arabidopsis and transient injection in walnut showed that both MYB27 and MYB113 were located in the nucleus and promoted anthocyanin accumulation,while MYB27 promoted the expression of LDOX-2,and MYB113 promoted the expression of LDOX-3and UAGT-3.Yeast one-hybrid and electrophoretic mobility shift assays showed that MYB27 could only bind to the LDOX-2 promoter,while MYB113 could bind to the promoters of both LDOX-3 and UAGT-3.In addition,we also identified an HD-Zip transcription factor,ATHB-12,which is specifically expressed in the pericarp.After silencing the expression of ATHB-12,the R2 pericarp turned red,and MYB113 expression increased.Further experiments showed that ATHB-12 could specifically interact with MYB113 and bind to its promoter.This suggests that MYB27controls R1 coloration by regulating LDOX-2,while MYB113 controls R2 coloration by regulating LDOX-3 and UAGT-3,but ATHB-12 can specifically bind to and inhibit the MYB113 of the R2 pericarp so that it becomes unpigmented.This study reveals the anthocyanin biosynthetic mechanisms in two different types of red walnut and provides a scientific basis for the selection and breeding of red walnut varieties.

Transcriptome profiling of indole-3-butyric acid-induced adventitious root formation in softwood cuttings of walnut

Inducing adventitious root(AR)formation in mature walnut species(Juglans L.)is challenging.However,the AR formation of mature trees can be improved by rejuvenation.In rejuvenated cuttings,exogenous indole-3-butyric acid(IBA)is essential for AR formation,and the underlying mechanism is still not well understood.Therefore,we utilized transcriptome sequencing to investigate the mechanism of IBA-induced AR formation.Our results revealed that,in comparison to the control group,IBA treatment(9 mmol·L^(-1))significantly increased the endogenous indole-3-acetic acid(IAA)content,leading to an enhanced rooting rate.We performed RNA sequencing to identify differentially expressed genes(DEGs)between the IBA-treated and control(CK)groups at 1,2,3,and 5 days after cutting(DAC).The results showed that,compared to the control cuttings,there were 1539,889,785,and 984 up-regulated genes and 2791,2936,3017,and 1752 down-regulated genes,at 1,2,3,and 5 DAC,respectively.Analysis of RNA-seq data revealed that G-type ATP-binding cassette 36/37(ABCG36/37)and ATP-binding cassette subfamily D 1(ABCD1),associated with IBA transport,were down-regulated in the rejuvenation cuttings.In contrast,PIN-FORMED(PIN)and PINOID(PID),associated with auxin efflux,were up-regulated.We identified 49 auxin/indole-3-acetic acid(AUX/IAA)-encoding genes,including IAA1,IAA3,IAA5,IAA6,IAA8,IAA11,IAA12,IAA19,and IAA20,which were up-regulated at 1-5 DAC in the rejuvenated cuttings.This study highlights that the overexpression of JrWOX5/11 in poplar significantly enhance AR growth,as evidenced by increased root length,surface area,volume,and quantity.Moreover,the co-expression network analysis involving JrWOX11 and JrWOX5 in walnut cuttings elucidates complex genetic interactions,underscoring their pivotal role in the formation of AR.Our data supported the following molecular mechanism of IBA-induced adventitious root formation.Firstly,IBA is converted to free IAA in peroxisomes.Then,the highly concentrated IAA in the procambium and parenchyma cells induces WUSCHEL-related homeobox 11(WOX11)expression at two days.Finally,WOX11 acts redundantly to up-regulate WOX5,initiating the development of root primordia cells.

Exploration of cyclooxygenase-2 inhibitory peptides from walnut dreg proteins based on in silico and in vitro analysis

Walnut dreg protein hydrolysates(WDPHs)exhibit a variety of biological activities,however,the cyclooxygenase-2(COX-2)inhibitory peptide of WDPHs remain unclear.The aim of this study was to rapidly screen for such peptides in WDPHs through a combination of in silico and in vitro analysis.In total,1262 peptide sequences were observed by nano liquid chromatography/tandem mass spectrometry(nano LC-MS/MS)and 4 novel COX-2 inhibitory peptides(AGFP,FPGA,LFPD,and VGFP)were identified.Enzyme kinetic data indicated that AGFP,FPGA,and LFPD displayed mixed-type COX-2 inhibition,whereas VGFP was a non-competitive inhibitor.This is mainly because the peptides form hydrogen bonds and hydrophobic interactions with residues in the COX-2 active site.These results demonstrate that computer analysis combined with in vitro evaluation allows for rapid screening of COX-2 inhibitory peptides in walnut protein dregs.

Population genetic insights into the conservation of common walnut(Juglans regia)in Central Asia

The common walnut(Juglans regia)is one of the most economically important nut trees cultivated worldwide.Despite its importance,no comprehensive evaluation of walnut tree population genetics has been undertaken across the range where it originated,Central Asia.In this study,we investigated the genetic diversity and population structure of 1082 individuals from 46 populations across Central Asia.We found moderate genetic diversity of J.regia across Central Asia,with 46 populations clustered into three groups with a weak relationship between genetic and geographic distance.Our findings reveal that the western Himalaya might be the core region of common walnut genetic diversity in Central Asia and that,except for two populations in Gongliu Wild Walnut Valley,humans might have introduced walnut populations to Xinjiang,China.The observed distribution of the genetic landscape has probably been affected by historical climate fluctuation,breeding system,and prolonged anthropogenic activity.We propose the conservation of the core genetic diversity resources in the western Himalaya and pay special attention to populations from Gongliu in Xinjiang.These findings enhance our understanding of the genetic variation throughout the distribution range of J.regia in Central Asia,which will provide a key prerequisite for evidence-based conservation and management.

Chemical composition of walnuts from three regions in China

To reveal the characteristic chemicals of walnuts from different origins, we analyzed fatty acid composition,tocopherols, phytosterols and total phenolic content (TPC) of walnuts from three main producing regions inChina. The results showed that walnuts were rich in polyunsaturated fatty acids, and the ratio of ω-6 to ω-3 fattyacids was close to the recommendation of Chinese Nutrition Society. Moreover, walnuts contain high contents oftocopherols (331.20–414.71 mg/kg), phytosterols (97.17–110.35 mg/100 g) and phenols (38.51–48.08 mg GAE/kg). Significant chemical differences exist among walnuts from three production regions. The highest content ofpolyunsaturated fatty acids was found in walnuts from the northern China, the highest content of tocopherols inwalnuts from southwest China, and the highest contents of phytosterol and TPC in walnuts from northwest China.However, there was no significant difference in the tocopherol, phytosterol and TPC content of walnuts betweenthe Northern China and Northwest China. The above results provide important references for manufacturers andconsumers to select suitable walnut scientifically and reasonably.

The Physiological and Molecular Responses of Exogenous Selenium to Selenium Content and Fruit Quality in Walnut

To study the effect of exogenous selenium on fruit quality in walnut(Juglans regia L.),8-year-old walnut(Qingxiang)was taken as the research object.In the fruit expansion stage,300 mg/L of sodium selenate,yeast selenium and sodium selenite solutions were applied on the leaf of walnut,and the selenium levels in leaves,pericarp and kernel were determined at the ripening stage.The fruit quality,mineral nutrient content,antioxidant enzyme activity,and related genes’expression were analyzed.The results showed that the three exogenous selenium increased the selenium levels in leaves,pericarp and kernel of walnut.They also significantly increased fruit and kernel weights,and kernel linoleic acid,but markedly decreased kernel crude fat and saturated fatty acid.Selenium spraying promoted the absorption of mineral nutrients such as potassium and zinc,but inhibited the absorption of calcium,and had no significant effect on iron and magnesium in the kernel.Three exogenous selenium increased the activities of superoxide dismutase(SOD),peroxidase(POD),ascorbate peroxidase(APX),and catalase(CAT)significantly in the kernel.Except for sodium selenate treatment significantly reduced malondialdehyde(MDA)content in the kernel,the other two selenium sources treatments had no significant effect on MDA and hydrogen peroxide(H2O2)levels.They also increased the expression of JrCu/Zn-SOD,Jr2-Cys POD,JrCyt-APX and JrCAT in kernel,to different extents.These implies that,in the walnut fruit enlargement period,the foliar spraying selenium could increase the selenium content of walnut,affect the mineral nutrient absorption,improve the antioxidant capacity and related genes’expression,and reduce the degree of peroxide,and then improve the quality of fruit.Furthermore,yeast selenium showed the comprehensive effect of the best.

Simulation Analysis of Stress Field of Walnut Shell Composite Powder in Laser Additive Manufacturing Forming

A calculation model of stress field in laser additive manufacturing of walnut shell composite powder(walnut shell/Co-PES powder)was established.The DFLUX subroutine was used to implement the moveable application of a double ellipsoid heat source by considering the mechanical properties varying with temperature.The stress field was simulated by the sequential coupling method,and the experimental results were in good accordance with the simulation results.In addition,the distribution and variation of stress and strain field were obtained in the process of laser additive manufacturing of walnut shell composite powder.The displacement of laser additive manufacturing walnut shell composite parts gradually decreased with increasing preheating temperature,decreasing laser power and increasing scanning speed.During the cooling process,the displacement of laser additive manufacturing of walnut shell composite parts gradually increased with the increasing preheating temperature,decreasing scanning speed and increasing laser power.

Synthesis of Modified Walnut Shell Biochar and Its Performance of Cadmium Adsorption

Biochar is a functional and environmentally friendly material mainly made from by-products of industrial and agricultural production as raw material, which is cracked at high temperatures and slow speeds. The preparation of biochar requires the thermochemical conversion of biomass in an oxygen-restricted environment. Different raw materials and preparation processes result in biochar with different internal structures and biofunctional groups, which often have different properties. Adsorption of heavy metal pollutants is one of the main research directions for biochar application, and there are still areas that can be improved in the current research for biochar for treating heavy metal wastewater. In this study, we take the treatment of cadmium-containing wastewater as an example, walnut shell biochar (WSBC) as a carrier, iron(VI) compounds as a modifying reagent, and test the performance of cadmium-containing wastewater treatment using simulated cadmium-containing wastewater by adjusting the pyrolysis process and modification method at the same time to find the optimal experimental scheme, and give a reasonable theoretical explanation in relation to the results of the characterization tests, such as SEM, FT-IR, and so on. The characterized results show that iron(VI) compound (K2FeO4)-modified WSBC has a significant ability to remove cadmium contamination in the wastewater (remove 96.62% of cadmium in 1 minute), and its structure is different from other iron compound-modified ones. The aim of this study is to improve the efficiency of cadmium adsorption by specific types of biochar, while realizing the whole process as environmentally friendly as possible.

Characterization of Unsaturated Polyester Filled with Waste Coconut Shells, Walnut Shells, and Carbon Fibers

This study aims to evaluate the erosion behavior and the hardness of hybrid composites made of varying amounts of coconut shells,walnut shells,and carbonfibers dispersed in a polyester matrix.MINITAB(L16)Taguchi experiments were used to determine the optimal combination of parameters.In particular,an erosion device con-sisting of a motor with a constantflow rate of 45 L/min,a pump with a diameter of 40 mm,a nozzle with a dia-meter of 5 mm,and a tank made of“perspex glass”55 cm long,30 cm tall,and 25 cm wide was used.The tests were conducted by varying the sample-to-nozzle distance,the pattern angle,and the sand particle size.The results have revealed that the presence of 7.5%by weight of waste coconut shell,for conditions corresponding to 90°angle,sand size 425μm,stand distance 30 cm,gives the best wear resistance(3.04×10^(-5) g/g).Thefiller content and sand particle size affect the erosive rate,with the angle playing a secondary role.The distance between the sample and the nozzle has a weaker effect on erosive wear.The hardness results show that the models(UP-5%carbonfiber-2.5-3.5-4.5-5.5-6.5-7.5 wt.%waste coconut shell)give the best values for prayer compared to the samples(UP-5 wt.%carbonfiber-2.5-3.5-4.5-5.5-6.5-7.5 wt.%waste walnut shell).

云南不同品种核桃果实品质分析与综合评价

为了探究云南主栽核桃和薄壳山核桃果实的品质评价指标,选取27个核桃品种果实,对矿质元素、蛋白脂、粗脂肪等12个营养指标进行变异和相关性分析,并采用主成分和聚类分析方法,进行分类与综合评价。结果表明:12个营养指标的含量变异较为丰富,变异系数的变化范围为5%~83%,其中VC变异系数最大,粗脂肪变异系数最小;9种矿质元素平均含量从高到低依次为:K>P>Mg>Ca>Mn>Na>Fe>Zn>Cu,蛋白质含量均值为15.62%,脂肪含量均值为68.63%,VC的平均含量为4.66 mg/100 g;相关性分析表明,12个营养指标之间,P、Fe、Mg、Ca、Cu均与蛋白质呈极显著(P<0.01)正相关;主成分分析进行综合评价筛选出品质最佳的核桃品种为‘香茶’‘永平’‘晚熟’和‘小圆果’,薄壳山核桃中品种‘卡多’综合表现较好;聚类分析结果显示,可将其分为两大类,即富含矿质元素类群和高脂肪含量类群;相关性分析和主成分分析结果显示,K、Fe、Mg、Ca、Cu元素、蛋白质、脂肪为评价云南不同品种核桃品质的关键性指标。薄壳山核桃适合榨油,22种主栽核桃适合直接食用或开发富矿质元素和高蛋白的功能饮料。研究明确了云南核桃品质评价的关键指标并探明品质特性,提供科学分类方法,为云南核桃品质评价体系的构建奠定理论依据。

基于EDEM的核桃壳仁混合物振动筛分级工艺优化

为提高核桃壳仁混合物的分级效果,对现有核桃壳仁混合物分级设备进行三维实体建模,利用EDEM软件模拟核桃壳仁混合物的分级过程,以筛面上物料的运动速度、质量以及各等级颗粒在统计区域的数量为指标,以振幅、振动频率、振动方向角、筛面倾角为考察因素,对振动筛分级工艺进行优化。结果表明:在振动频率12 Hz、振幅5 mm、振动方向角45°、筛面倾角4°的工艺参数组合下,各等级核桃壳仁的透筛率最高,分级效果最好。

不同施肥处理对‘渝城1号’核桃产量、品质和土壤肥力的影响

以‘渝城1号’核桃为研究对象,设置单施复合肥、单施有机肥、施用核桃配方肥及不施肥4个处理,测定不同施肥处理时核桃产量、品质及核桃园土壤理化性质、微生物数量等,对核桃配方肥的应用效果进行评价。结果表明:施复合肥、有机肥及核桃配方肥均能提高核桃产量,其中,施用核桃配方肥的增产效果最好,经济效益最高,该施肥处理比不施肥的收益提高88.1%。相比于不施肥,施用核桃配方肥时核桃果实的蛋白质及脂肪总量显著提高,油酸、亚油酸、α-亚麻酸等不饱和脂肪酸占比增加,硬脂酸、棕榈酸等饱和脂肪酸占比下降。施用复合肥能促进核桃园土壤有效氮、磷、钾质量分数的增加,但会引起土壤pH及有机质质量分数下降。施用有机肥和核桃配方肥均能促进土壤有机质和有效养分质量分数增加。施用核桃配方肥后,土壤总微生物量增加,固氮菌、解磷菌、解钾菌、纤维降解菌等功能微生物数量均显著增多,土壤脲酶、磷酸酶、蔗糖酶、过氧化氢酶等活性大幅升高。施用核桃配方肥能显著提升核桃的产量和品质,更利于土壤养分转化和果园可持续经营。

青皮核桃采摘机械臂设计与仿真

针对大多数核桃种植区采摘核桃仍为人工采摘,效率低下、用工多等问题,设计了一种机械臂和末端执行器协作的采摘装置。首先,采用SolidWorks建立虚拟样机,对末端执行器进行受力分析并且利用ANSYS Workbench中的Static Structural模块对末端执行器关键部件进行静力学分析,得到手指最大应力为17.69 MPa,能够完成果实抓取任务。然后,采用D-H法对机械臂建模,使用MATLAB软件的机器人工具箱(Robotics Toolbox)进行建立机械臂数字模型,并对其进行工作区间分析和轨迹规划仿真。结果表明,所选机械臂和末端执行器能够满足设计要求。

核桃青皮粉及其提取物对猪生长性能、胴体性状和肉品质的影响

【目的】研究核桃青皮粉及其提取物对育肥猪生长性能、胴体和肉质性状的影响。【方法】选取90头健康、体重约80 kg的“杜×长×大”三元杂交育肥阉公猪,随机分为3组,每组3个重复,每个重复10头猪。对照组育肥猪饲喂基础饲粮,核桃青皮粉试验组及其提取物试验组分别在基础饲粮中添加0.1%核桃青皮粉和0.1%核桃青皮粉提取物。预试期10 d,正试期40 d。试验第41天,测定每头猪初始体重、终末体重及各组采食量。试验结束后,每个重复中选取2头体重接近平均体重的试验猪进行屠宰,测定胴体性状、肉质性状,以及背最长肌的氨基酸和脂肪酸含量。【结果】与对照组相比,饲粮中添加核桃青皮粉或其提取物对育肥猪末重、平均日增重、平均日采食量、料重比、胴体直长、胴体斜长、胴体重、屠宰率、眼肌面积、板油重以及背最长肌pH_(45 min)、滴水损失、加压损失、大理石纹评分、红度均无显著影响(P>0.05),但可显著提高育肥猪背膘厚、背最长肌黄度和肌内脂肪含量(P<0.05)。与对照组相比,除了组氨酸,核桃青皮粉组育肥猪背最长肌中其他氨基酸含量均有一定提高,而核桃青皮提取物组的氨基酸含量与对照组的差异不大,核桃青皮粉组和提取物组多不饱和脂肪酸总含量均比对照组含量有一定提高。【结论】饲粮添加0.1%核桃青皮粉及其提取物对生长性能和胴体性状无负面影响,二者均可改善育肥猪肉质性状,核桃青皮粉效果更佳。

重庆核桃种质资源表型性状多样性分析

【目的】分析重庆核桃种质资源表型性状多样性,为重庆核桃种质资源客观评价及合理开发利用提供理论参考。【方法】从重庆地区收集了16个实生居群(产区)的181份核桃种质资源,依据国家标准及行业标准对其植株和坚果的28个表型性状(17个质量性状和11个数量性状)进行测定,并分析其变异系数、遗传多样性及各表型性状间的相关性,最后基于表型性状进行聚类分析。【结果】181份核桃种质17个质量性状的Simpson指数和Shannon-Wiener指数分别为0~0.87和0~1.93,其中以小叶形状、树冠、核壳表面特征和核仁皮色的多样性较丰富;11个数量性状的变异系数介于8.70%~53.70%,其中单枝结果数变异系数最大,果形指数变异系数最小。16个实生居群181份核桃种质的28个表型性状变异系数为0~67.90%,平均为19.79%;各居群间表型性状变异系数为15.20%~26.38%。181份核桃种质的多样性来源于居群内变异和居群间变异,但居群内的变异起主要作用,且坚果表型性状的变异较其他性状更大。相关分析发现,11个数量性状间的相关系数有29对达到显著(P<0.05,下同)或极显著(P<0.01,下同)水平,核桃表型数量性状间存在丰富的相关,其中显著正相关的性状有24对,显著负相关的性状有5对。聚类分析结果显示,当遗传距离为22.5时,可将181份核桃种质分为三大类群,来自同一地区的材料分散于各类群中,聚类结果无明显地域性。【结论】重庆具有丰富的核桃种质资源,核桃表型多样性高,其表型变异主要来源于居群内变异;重庆核桃种质资源的亲缘关系与地理来源无明显相关性。

‘陇核5号’果实发育规律及疏果施肥对坚果品质的影响

【目的】明确核桃果实发育规律及影响坚果品质的因素,为核桃果园生产管理提供参考。【方法】以‘陇核5号’为研究对象,对其果实发育过程中外观形态变化进行拍照记录,测定果实三径、果实质量、果皮厚度、坚果三径、坚果质量、核仁质量、出仁率、壳厚等指标,利用Logistic方程、二次方程、三次方程等模型对各指标变化趋势进行拟合。通过疏果和不同时期喷施叶面肥,分析不同处理对核桃坚果经济性状的影响。【结果】在发育过程中,果实(坚果)大小和质量均表现为缓慢增长、迅速增长、缓慢增长的趋势,其中果实质量分别在花后50 d时和花后100 d时出现了增长高峰,坚果质量在花后110 d时出现了增长高峰。花后30~40 d时果实缓慢增长,随后迅速膨大,果实质量快速增加,花后50 d时开始出现水状核仁,花后70 d时硬核开始出现;花后70 d后,果实大小和质量增长变慢,果壳开始形成并逐渐硬化变厚;花后90~120 d时,坚果质量、果壳厚度、核仁质量及出仁率等指标均快速增加;花后120~140 d时,坚果大小增长速度变慢,坚果质量开始下降。方差分析结果表明,除坚果三径外,其他指标在不同处理间差异显著(P<0.05)。其中以7月初—8月初喷施叶面肥处理下核桃坚果经济指标值最高且与对照差异极显著(P<0.01);其次是5月底—6月底喷施叶面肥,与对照差异显著(P<0.05);疏果处理下核桃坚果经济指标与对照差异不显著(P>0.05)。【结论】‘陇核5号’果实生长发育总体为缓慢、快速、缓慢的趋势,呈单“S”形曲线。疏果、施肥均能改善核桃坚果的经济性状。

核桃振动采收研究现状与发展趋势

核桃作为一种高附加值的经济作物,具有广泛的市场需求和良好的经济效益。随着我国核桃种植面积的不断扩大和农业机械化的发展,核桃采收存在的采收率低下、采净率不高的问题日渐凸显,研制适合我国不同种植模式需求的核桃高效采收装备对于促进核桃生产规模化、推进农业科技创新具有重要意义。针对国内外核桃采收技术与装备的发展,综述了对于立地条件复杂的山核桃、小行距矮化密植种植模式下的核桃以及标准果园种植模式下的核桃适用的机械采收设备的研究现状,从树枝振动、树干振动和树冠振动3个角度对其振动机理进行了分析论证,并就国内外振动采收的激振夹持方式与激振参数进行了分析。分析了当前振动采收技术在实际应用过程中存在的主要问题,并指出了结构复杂、工作参数难确定、智能化程度不高是制约我国核桃采收机械发展的因素。提出了未来核桃振动采收智能化、多样化的发展趋势,通过在激振机理、能量传递、精准定位、柔性作业等方面开展深入研究,可为振动采收技术与装备的发展提供一种新思路。

核桃机械化收获装置研究现状与展望

核桃是我国重要的经济作物,其收获具有采收时间短、收获环境复杂等特点。随着近年来我国核桃产量的快速增长,现有的收获技术制约着核桃产业的发展,核桃机械化收获存在的问题逐渐凸显,核桃机械化收获体系亟需完善。国内外现有的核桃机械收获装置可分为分段式与采收一体式,通过总结核桃机械化收获装置的结构、特点以及工作原理,指明现阶段核桃机械化收获装置存在自动化水平不足、装置集成化程度低、地形适应能力不足、作业效果差等问题,并对核桃机械化收获装置未来的发展提出建议,为核桃机械化收获装置的改进与创新提供方向与思路。未来核桃收获机械的发展应全面面向自动化、智能化、集成化、拥有更强的适应性与可靠性,以满足不断发展的核桃产业的需求。

山核桃破壳裂纹试验与仿真分析

研究山核桃在冲击力下裂纹产生和发展的规律。用万能力学试验机进行冲击破壳试验,分别对山核桃在长轴、斜向和短轴加载方向各进行3种不同高度的15次重复试验。结果表明,无论加载方向如何,破壳冲击力的最大值都在240 N左右,且越靠近横轴方向力越小,越靠近长轴方向力越大。以此为依据,将山核桃横向截面简化为圆形,通过在传统弹塑性元素接触模型基础上增加强结合力的方法,构建压头—山核桃离散单元模型。仿真结果显示,水平压头会造成山核桃模型对称裂纹形式被压溃;与此同时,竖直状态压头会以S型裂纹形式分裂山核桃模型。通过高速摄像机拍摄山核桃破壳裂纹产生过程,与仿真结果基本一致。为山核桃破壳机械的设计、优化与深入地理解山核桃裂纹产生与发展机理提供重要参考。