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1.
广义矩阵迹的贝尔曼不等式   总被引:3,自引:0,他引:3  
引入了广义矩阵迹τ:Mn(C(Ω))→C(Ω),讨论了在广义矩阵迹下的贝尔曼不等式。证明了C^*-代数Mn(C(Ω))中任意两个正元A,B及A k∈N,有τ((AB)^k)≤τ(A^kB^k),这便在更一般的框架下给出了Bellman问题的一个肯定问题。同时还利用C^*-代数证明了其它一些相关不等式。  相似文献   

2.
矩阵不等式是矩阵理论中一类重要问题.利用半正定矩阵的Shut定理,讨论了对任意凹函数和n×n阶矩阵的范数不等式,得到一些关于Roffel型迹范数不等式新的结果.并且使得文献中的一个定理是本文的一个推论.所得含有Roffel型迹范数不等式可用于其他矩阵不等式方向的研究.  相似文献   

3.
王丹 《针织工业》2015,(8):54-57
采用正交试验原理设计试验,测试分析缝线品种、线迹类型和线迹密度对针织服装缝制牢度和外观质量的影响。经过测试和数据分析得出:涤纶缝线(A2)的强度、延伸性、均匀性和耐磨性均好于棉线及涤棉混纺线;双针绷缝线迹(B3)的拉伸性能大于301号线迹和三线包缝线迹;301号线迹(B2)的耐磨性好于双针绷缝线迹和三线包缝线迹;线迹密度为4针/cm(C2)时拉伸性能和耐磨性能较好。因此,考虑拉伸性,A2B3C2为最优参数组合;考虑耐磨性能,A2B2C2为最优参数组合,此结论对于提升针织服装缝制牢度及服用性能具有技术指导性。  相似文献   

4.
研究亚纯函数与其k阶导数分担一个IM公共值和一个CM公共值在一定条件下的惟一性问题,考虑吴桂荣有关亚纯函数及其k阶导数具有1CM公共值在一定条件下的惟一性问题,利用构造辅助函数结合Nevanlinna第二基本定理的方法证明了:设f与g为非常数亚纯函数,1为f(k)与g(k)的CM公共值,k∈N,∞为f与g的IM公共值,如果(k+1)-Nr,1f+(k+1)-Nr,1g+2(k+1)N-(r,f)+(1/2)N-D(r,f)(λ+o(1))T(r)(r∈I),其中λ1/2,T(r)=max{T(r,f),T(r,g)},-ND表示相应于f与g所有极点的重级均不相同的f极点的精简密指量,则f(z)≡g(z)或者f(k)(z).g(k)(z)≡1.  相似文献   

5.
根据已有的关于左不可数语言以及(n,k)-语言的研究成果.本文考虑当k=2时,(n,2)-语言和左-(n,2)-语言的一些性质,得出:(1)设A,B是阶分别为k1和k2的左-(n,2)-语言,则AB是阶为k1+k2的左-(n,2)-语言;(2)AB是(n,2)-语言(或左-(n,2)-语言),若A是左奇异语言,则B是(n,2)-语言(或左-(n,2)-语言);(3)左-(n,2)-语言的集合在连接运算,并集,交集和补集运算下是封闭的.  相似文献   

6.
运用Kloosterman和、特征和以及三角和的一些基本性质和估计得到了k-free数与其逆的差的一个渐近公式.并且证明了:当k≥2,m≥2,n2,n∈N,k∈N,m∈N,ε0时,M(n,m;k)=2φ(n)nm/ζ2(k)(m+1)(m+2)+O(2mnm+1/2+2/(k+1)+2εd(n)σ-1/2(n)σ(n)).特别是当k=2时,有无平方因子数与其逆的差:M(n,m;2)=72φ(n)nm/π4(m+1)(m+2)+O(2mnm+1/2+2/(k+1)+2εd(n)σ-1/2(n)σ(n).此处的d(n)表示因数函数,(n)表示欧拉函数.  相似文献   

7.
讨论了Banach空间中(p,Y)-算子Bessel列,(p,Y)-算子框架及(p,Y)-算子Riesz基的稳定性.利用算子理论和代数的方法,将Casazza和Christensen的Hilbert空间框架的不等式形式稳定性条件推广到Banach空间,证明了(p,Y)-算子Bessel列,(p,Y)-算子框架及(p,Y)-算子Riesz基保持稳定性的不等式条件,并给出几种等价形式的不等式条件.  相似文献   

8.
利用D.A.Goldston的方法,研究奇数哥德巴赫问题的奇异级数的余项槇Sy(k),得到了其求和的渐近公式:∑k≤(N-k)2Sy(k)2=T(y)N3/3(1+Oδ((y2/N)δ))  相似文献   

9.
对于整数k,l≥0,用D(k,l)表示一类有向图的集合,这类图的每个顶点要么入度不超过k要么出度不超过l.研究了度条件下有向图中的最大有向割问题,目的是确定图类D(k,l)中有向图的最大有向割包含的弧的条数.对于包含m条弧的有向图,通过分析图的结构,采用数学归纳法,得到(1)若D∈D(2,3)∪D(3,2),则存在至少包含2m/7条弧的有向割;(2)设D∈D(k,k),若存在顶点集的一个二部划分(X,Y),使得X中点的入度与Y中点的出度都不超过k,并且起点在X中终点在Y中的弧的集合的导出图的基础图不含圈,则存在至少包含(1/4+1/(8k+4))m条弧的有向割.  相似文献   

10.
0 引言M_n(f,x)=sum from k=0 to ∞ f(k/n+k)M_(nk)(x),0≤x≤1.(0.1)其中 M_(nk)(x)=((n+k-1)/k)x~k(1-x)~n陈文忠和郭顺生研究了 M_n(f,x)对[0,1]上的有界变差函数的点态逼近度,证得定理1 设 f∈B∨[0,1],x∈(0,1)。则当 n 充分大时,有  相似文献   

11.
Since grapevine ( Vitis spp .) rootstock material is being traded increasingly as disbudded woody material a lack of distinctive morphological features on such material necessitates an alternative and reliable means of identification. Methods described here were developed for rapid and efficient extraction of DNA from woody samples rich in phenolic compounds and polysaccharides, and for subsequent identification of varieties by RAPD PCR. Using these methods, and with the application of only one selected RAPD primer, we were able to differentiate sixteen rootstock varieties, including the seven varieties most commonly used in Germany. Problems commonly encountered with reproducibility of RAPD patterns were avoided by choosing primers with a dinucleotide sequence and a high G/C content that allowed a rather high annealing temperature of 45°C. Methods described here should also be useful for other horticultural crops, especially those with woody tissues rich in phenolic compounds and polysaccharides.  相似文献   

12.
An internet website (http://cpf.jrc.it/smt/) has been produced as a means of dissemination of methods of analysis and supporting spectroscopic information on monomers and additives used for food contact materials (principally packaging). The site which is aimed primarily at assisting food control laboratories in the European Union contains analytical information on monomers, starting substances and additives used in the manufacture of plastics materials. A searchable index is provided giving PM and CAS numbers for each of 255 substances. For each substance a data sheet gives regulatory information, chemical structures, physico-chemical information and background information on the use of the substance in particular plastics, and the food packaging applications. For monomers and starting substances (155 compounds) the infra-red and mass spectra are provided, and for additives (100 compounds); additionally proton NMR are available for about 50% of the entries. Where analytical methods have been developed for determining these substances as residual amounts in plastics or as trace amounts in food simulants these methods are also on the website. All information is provided in portable document file (PDF) format which means that high quality copies can be readily printed, using freely available Adobe Acrobat Reader software. The website will in future be maintained and up-dated by the European Commission's Joint Research Centre (JRC) as new substances are authorized for use by the European Commission (DG-ENTR formerly DGIII). Where analytical laboratories (food control or other) require reference substances these can be obtained free-ofcharge from a reference collection housed at the JRC and maintained in conjunction with this website compendium.  相似文献   

13.
The characterization of the aromatic profile of several apricot cultivars with molecular tracers in order to obtain objective data concerning the aromatic quality of this fruit was undertaken using headspace–solid phase microextraction (HS–SPME). Six apricot cultivars were selected according to their organoleptic characteristics: Iranien, Orangered, Goldrich, Hargrand, Rouge du Roussillon and A4025. The aromatic intensity of these varieties measured by HS–SPME–Olfactometry were defined and classified according to the presence and the intensity of grassy, fruity and apricot like notes. In the six varieties, 23 common volatile compounds were identified by HS–SPME–GC–MS. Finally, 10 compounds, ethyl acetate, hexyl acetate, limonene, β-cyclocitral, γ-decalactone, 6-methyl-5-hepten-2-one, linalool, β-ionone, menthone and (E)-hexen-2-al were recognized by HS–SPME–GC–O as responsible of the aromatic notes involved in apricot aroma and considered as molecular tracers of apricot aromatic quality which could be utilized to discriminate apricot varieties.  相似文献   

14.
The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 μm-thick oriented PP) into the food simulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.  相似文献   

15.
BADGE.2HCl and BFDGE.2HCl were determined in 28 samples of ready-to-drink canned coffee and 18 samples of canned vegetables (10 corn, 5 tomatoes and 3 others), all from the Japanese market. HPLC was used as the principal analytical method and GCMS for confirmation of relevant LC fractions. BADGE.2HCl was found to be present in one canned coffee and five samples of corn, BFDGE.2HCl in four samples of canned tomatoes and in one canned corn. No sample was found which exceeded the 1mg/kg limit of the EU for the BADGE chlorohydrins. However the highest concentration was found for the sum of BFDGE.2HCl and BFDGE.HCl.H2O at a level of 1.5mg/kg. A Beilstein test confirmed that all cans containing foods contaminated with BADGE.2HCl or BFDGE.2HCl had at lest one part coated with a PVC organosol.  相似文献   

16.
17.
A strong science base is required to underpin the planning and decision-making process involved in determining future European community legislation on materials and articles in contact with food. Significant progress has been made in the past 5 years in European funded work in this area, with many developments contributing to a much better understanding of the migration process, and better and simpler approaches to food control. In this paper this progress is reviewed against previously identified work-areas (identified in 1994) and conclusions are reached about future requirements for R&D to support legislation on food contact materials and articles over the next 5 or so years.  相似文献   

18.
19.
This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.  相似文献   

20.
<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of the  相似文献   

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