改进的Preisach-DOK模型对钡铁氧体Henkel曲线的研究

利用改进的Preisach-DOK模型模拟得到了纵向钡铁硬磁盘及γ-Fe2O3软盘的Henkel曲线和Δm曲线.研究发现钡铁氧体粒子之间具有很强的“正”相互作用,起到了阻止退磁的作用,说明钡铁氧体具有较好的剩磁特性.     

改进的Preisach-DOK模型对钡铁氧体剩磁特性的研究

利用改进的Preisach-DOK模型模拟得到了纵向钡铁硬磁盘及γ-Fe2O3软盘的磁滞回线、剩磁回线、可逆曲线,分析了两种样品的剩磁特性．研究发现钡铁氧体的矫顽力主要由磁晶各向异性决定,大于主要由形状各向异性决定的γ-Fe2O3的矫顾力．同时钡铁氧体具有高的Sr,小的SP75和窄的SFDr,说明其具有较好的剩磁特性．     

M型钡铁氧体/氧化石墨烯复合吸波材料的磁性能与吸波性能（英文）

为了提高M型钡铁氧体吸波材料的吸波性能,通过溶胶-凝胶和自蔓延高温合成法制备了不同氧化石墨烯含量的M型钡铁氧体/氧化石墨烯复合吸波材料.借助X射线衍射仪、扫描电子显微镜、物理性能测试仪和矢量网络分析仪对M型钡铁氧体/氧化石墨烯复合吸波材料的晶体结构、表面形貌、磁性能和吸波性能分别进行了研究.研究表明:M型钡铁氧体/氧化石墨烯复合吸波材料的吸收频段不仅比M型钡铁氧体材料宽,而且吸收强度比M型钡铁氧体大,其中掺杂氧化石墨烯含量为3%的样品,在10~18 GHz的频率上,反射率最小.因此,加入氧化石墨烯有效地改善了M型钡铁氧体的吸波性能.     

温室固相法制备M型超细钡铁氧体的研究

以FeCl3·6H2O、Ba(NO3)2和NaOH为原料,采用固相法合成了M型超细钡铁氧体.通过TGA/SD-TA、扫描电子显微镜(SEM)和X射线衍射仪(XRD)进行了分析和表征.结果表明:前驱体在900℃进行煅烧,合成了以M型钡铁氧体BaFe12O19为主,含有少量BaFe2O4>的起细粉体,粒子粒度较为均匀,粒晶在100nm左右,分散性较好.     

柠檬酸溶胶-凝胶法制备纳米钡铁氧体及其磁性能

以柠檬酸为络合剂,利用溶胶-凝胶法制备了M型钡铁氧体纳米粉体,研究了柠檬酸掺量、溶胶pH值等参数对粉体晶体结构与磁性能的影响.利用X射线衍射仪、振动样品磁强计对所得样品的结构与磁性能进行了表征与分析.结果表明:柠檬酸与金属离子摩尔比为2:1,溶胶pH值为9,煅烧温度为900℃的条件下制备的钡铁氧体纳米粉体,结晶良好,晶粒尺寸41 nm,矫顽力达到最大值,6053 Oe.     

磁记录材料的生产工艺

阐明了r—Fe_2O_3,磁粉、CrO_2磁粉、钡铁氧体磁粉、金属(合金)磁粉等磁记录材料的生产工艺和技术关键。     

磁场对磁流体红外吸收的影响

本文测量了三种磁流体在外加磁场前后的红外反射吸收谱,发现磁流体的红外吸收系数随磁粉浓度的增加而增加,在外磁场作用下吸收系数降低,钡铁氧体和锰锌铁氧体磁液随外磁场增加吸收系数单调下降并趋向一渐近值,Fe—Ni合金磁流体的吸收系数随磁场的变化出现异常。采用链状结构模型和理论可解释上述现象。     

双星不是形成钡星的充分条件

讨论了双星是否是产生钡星的必要和充分条件,因为已知道的钡星系统全是双星.根据钡星的形成机制,双星确实是形成钡星的必须条件,但是在一些具有和钡星系统相似轨道根数的双星中,存在普通巨星,这充分说明双星不是产生钡星的充分条件.     

用铁氧体电感线圈作串联谐振

用铁氧体电感线圈作串联谐振实验，其谐振曲线左右不对称，谐振峰较平滑，且谐振点随外加电源电压的大小而改变．为了分析这种现象，用实验测出铁氧体电感线圈的伏安特性曲线，并且在同一座标系上作出整个串联谐振电路的伏安特性曲线，根据曲线的变化规律，解释了实验现象．     

新型振动样品磁强计测量材料磁性

简述新型振动样品磁强计测量原理,介绍自制的采用电动机驱动的振动样品磁强计,并通过用已知饱和磁矩的镍球对仪器进行定标,分别测量了铁氧体多晶小球和普通小钢球的磁化曲线,取得理想的实验结果.自制新型振动样品磁强计具有测量信号大和能判定磁矩方向的特点,该仪器可应用于高校近代物理实 验的教学.     

卡思卡特城堡

It is worthy of noting that, whilst Crookston Castle witnessed the earlier and happier portion of Mary's variegated life,     

不同的吃喝玩乐

一、吃和喝吃苹果 eat an apple, 吃药 take medicine,吃糖 have some sweets,吃饭 have one's meals,吃馆子 dine out,吃惊 be surprised/     

漏洞百出的教育

Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help?     

Western and Eastern culture differences in commercial field

The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity.     

只要努力,不要后悔

There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love.     

浅谈移民问题

Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject.     

风的曲线

Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose.     

团图为数的图中的闭团贯数

Given a graph G,a subgraph C is called a clique of G if C is a complete subgraph of G maximal under inclusion and |C|≥2. A clique-transversal set S of G is a set of vertices of G such that S meets all cliques of G. The clique-transversal number, denoted as TC (G), is the minimum cardinality of a clique-transversal set in G. The clique-graph of G, denoted as K (G), is the graph obtained by taking the cliques of G as vertices, and two vertices are adjacent if and only if the corresponding cliques in G have nonempty intersection. Let F be a class of graphs G such that F={G|K(G) is a tree}. In this paper the graphs in F having independent clique-transversal sets are shown and thus TC (G)/|G|≤1/2 for all G ∈ F.     

Sister Carrie, an Adherent of Desires

Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities.