Pub Date : 1967-09-01DOI: 10.1088/0508-3443/18/9/315
J. Groeneweg, H. Hiroyasu, R. Sowls
A method of using a Q-switched laser as a light source for photographing droplets in a spray is described. A fluorescent dye in the liquid being sprayed was excited by the second harmonic of ruby light at 3471 A. Droplets as small as 10 μm, travelling with velocities as high as 50 m sec-1, were successfully photographed. A dynamic size calibration showed that reliable drop size information could be obtained from the spray photographs.
描述了一种使用调q激光器作为拍摄喷雾中液滴的光源的方法。被喷液体中的荧光染料被3471 A的红宝石光的二次谐波激发。小至10 μm的液滴以高达50 m / s / 1的速度运动，成功地拍摄到了这些液滴。动态尺寸校准表明，从喷雾照片中可以获得可靠的液滴尺寸信息。
{"title":"Fluorescent photography of droplets in a spray using a Q-switched laser as a light source","authors":"J. Groeneweg, H. Hiroyasu, R. Sowls","doi":"10.1088/0508-3443/18/9/315","DOIUrl":"https://doi.org/10.1088/0508-3443/18/9/315","url":null,"abstract":"A method of using a Q-switched laser as a light source for photographing droplets in a spray is described. A fluorescent dye in the liquid being sprayed was excited by the second harmonic of ruby light at 3471 A. Droplets as small as 10 μm, travelling with velocities as high as 50 m sec-1, were successfully photographed. A dynamic size calibration showed that reliable drop size information could be obtained from the spray photographs.","PeriodicalId":9350,"journal":{"name":"British Journal of Applied Physics","volume":"74 1","pages":"1317"},"PeriodicalIF":0.0,"publicationDate":"1967-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88528604","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1967-09-01DOI: 10.1088/0508-3443/18/9/317
M. Casarella, P. Laura, M. Chi
The boundary value problem for steady flow and heat transfer through ducts of arbitrary shape is investigated for the case of uniform wall temperature. The use of conformal mapping methods allows for a unified treatment of problems involving ducts of non-circular cross section. A simple approximate technique for solving the formulated eigenvalue problem is proposed. The method is illustrated for slug flows in complex cross sections of practical interest. It is shown that the technique is also applicable to non-uniform flows and the numerical results for the eigenvalues of the Graetz problem are in excellent agreement with the published data.
{"title":"On the approximate solution of flow and heat transfer through non-circular conduits with uniform wall temperature","authors":"M. Casarella, P. Laura, M. Chi","doi":"10.1088/0508-3443/18/9/317","DOIUrl":"https://doi.org/10.1088/0508-3443/18/9/317","url":null,"abstract":"The boundary value problem for steady flow and heat transfer through ducts of arbitrary shape is investigated for the case of uniform wall temperature. The use of conformal mapping methods allows for a unified treatment of problems involving ducts of non-circular cross section. A simple approximate technique for solving the formulated eigenvalue problem is proposed. The method is illustrated for slug flows in complex cross sections of practical interest. It is shown that the technique is also applicable to non-uniform flows and the numerical results for the eigenvalues of the Graetz problem are in excellent agreement with the published data.","PeriodicalId":9350,"journal":{"name":"British Journal of Applied Physics","volume":"54 1","pages":"1327-1335"},"PeriodicalIF":0.0,"publicationDate":"1967-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75376292","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1967-09-01DOI: 10.1088/0508-3443/18/9/308
W. Legler
The distribution of sizes of electron avalanches produced in a gas by an electric field at high values of E/p is influenced by the relaxation processes in the electron energy distribution after an ionization. The description of this influence requires an ionization coefficient which depends on the avalanche size n as well as on the distance from the cathode. Lack of information on this dependence prevents a rigorous calculation of the avalanche distribution. Recently Cookson and Lewis suggested a solution of the problem by the introduction of an ionization coefficient depending on n only. The present work shows that this proposal must be rejected for physical reasons. An approximate solution previously given by the author, which is based on the concept of an `individual' ionization coefficient, is compared with the Polya distribution discussed by Cookson and Lewis and other authors.
{"title":"The influence of the relaxation of the electron energy distribution on the statistics of electron avalanches","authors":"W. Legler","doi":"10.1088/0508-3443/18/9/308","DOIUrl":"https://doi.org/10.1088/0508-3443/18/9/308","url":null,"abstract":"The distribution of sizes of electron avalanches produced in a gas by an electric field at high values of E/p is influenced by the relaxation processes in the electron energy distribution after an ionization. The description of this influence requires an ionization coefficient which depends on the avalanche size n as well as on the distance from the cathode. Lack of information on this dependence prevents a rigorous calculation of the avalanche distribution. Recently Cookson and Lewis suggested a solution of the problem by the introduction of an ionization coefficient depending on n only. The present work shows that this proposal must be rejected for physical reasons. An approximate solution previously given by the author, which is based on the concept of an `individual' ionization coefficient, is compared with the Polya distribution discussed by Cookson and Lewis and other authors.","PeriodicalId":9350,"journal":{"name":"British Journal of Applied Physics","volume":"74 1","pages":"1275-1280"},"PeriodicalIF":0.0,"publicationDate":"1967-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73837532","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1967-09-01DOI: 10.1088/0508-3443/18/9/306
L. Crovini, S. Sartori
On the basis of theoretical considerations and with the support of experimental results, it has been concluded that the melting range of an extremely pure (69 grade) zinc sample is not uniquely defined. The use of a determined conventional melting range in standard conditions is proposed in order to classify zinc samples on the basis of total impurity content. Some comparison data of four zinc samples for the thermometric fixed-point determination are given.
{"title":"Thermal analysis of zinc samples for the thermometric fixed point","authors":"L. Crovini, S. Sartori","doi":"10.1088/0508-3443/18/9/306","DOIUrl":"https://doi.org/10.1088/0508-3443/18/9/306","url":null,"abstract":"On the basis of theoretical considerations and with the support of experimental results, it has been concluded that the melting range of an extremely pure (69 grade) zinc sample is not uniquely defined. The use of a determined conventional melting range in standard conditions is proposed in order to classify zinc samples on the basis of total impurity content. Some comparison data of four zinc samples for the thermometric fixed-point determination are given.","PeriodicalId":9350,"journal":{"name":"British Journal of Applied Physics","volume":"1 1","pages":"1261-1267"},"PeriodicalIF":0.0,"publicationDate":"1967-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90171180","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1967-09-01DOI: 10.1088/0508-3443/18/9/301
W. Wallace, W. J. Kitchingman
X-ray powder diffraction measurements of peak displacement and asymmetries from cold-worked face-centred cubic silver-zinc alloys have been used to investigate the role played by deformation stacking faults and twin faults respectively in the working process. Faults are shown to have considerable effect on the x-ray line broadening. The faulting probability varies parabolically with zinc content, reaching a maximum in the high solute content region of the phase field. Comparison of the results with those of other workers for silver-based alloys supports the view that the variation in faulting probability with composition is influenced by the position of the face-centred cubic phase boundary. Deformation stacking faults and twin faults show a similar variation with composition and lead to very small particle-size values at high zinc contents.
{"title":"Deformation faults in face-centred cubic silver-zinc alloys","authors":"W. Wallace, W. J. Kitchingman","doi":"10.1088/0508-3443/18/9/301","DOIUrl":"https://doi.org/10.1088/0508-3443/18/9/301","url":null,"abstract":"X-ray powder diffraction measurements of peak displacement and asymmetries from cold-worked face-centred cubic silver-zinc alloys have been used to investigate the role played by deformation stacking faults and twin faults respectively in the working process. Faults are shown to have considerable effect on the x-ray line broadening. The faulting probability varies parabolically with zinc content, reaching a maximum in the high solute content region of the phase field. Comparison of the results with those of other workers for silver-based alloys supports the view that the variation in faulting probability with composition is influenced by the position of the face-centred cubic phase boundary. Deformation stacking faults and twin faults show a similar variation with composition and lead to very small particle-size values at high zinc contents.","PeriodicalId":9350,"journal":{"name":"British Journal of Applied Physics","volume":"25 1","pages":"1221-1225"},"PeriodicalIF":0.0,"publicationDate":"1967-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87307534","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1967-09-01DOI: 10.1088/0508-3443/18/9/303
R. Easson, P. Hlawiczka
Measurements of flux penetration and dissipation at 50 c/s have been made on niobium samples shaped to approach closely the case of slab geometry with a tangential applied field. When corrected for end effects the measured quantities are independent of sample thickness, which varies from 0125 to 0004 in. Comparison of the experimental results with the Bean-London model yields little quantitative agreement.
{"title":"Flux penetration and a.c. losses in superconducting niobium","authors":"R. Easson, P. Hlawiczka","doi":"10.1088/0508-3443/18/9/303","DOIUrl":"https://doi.org/10.1088/0508-3443/18/9/303","url":null,"abstract":"Measurements of flux penetration and dissipation at 50 c/s have been made on niobium samples shaped to approach closely the case of slab geometry with a tangential applied field. When corrected for end effects the measured quantities are independent of sample thickness, which varies from 0125 to 0004 in. Comparison of the experimental results with the Bean-London model yields little quantitative agreement.","PeriodicalId":9350,"journal":{"name":"British Journal of Applied Physics","volume":"406 1","pages":"1237-1249"},"PeriodicalIF":0.0,"publicationDate":"1967-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91445168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1967-09-01DOI: 10.1088/0508-3443/18/9/304
A. Esin, W. Jones
The effective a.c. resistance of a conductor is a function of the frequency of the current and the resistivity and the permeability of the conductor. The resistivity and permeability are affected by strain and, by using a suitable high-frequency a.c. bridge, these effects can be amplified and measured as a function of strain. In this paper it is shown that the changes in the effective a.c. resistance which result from straining a ferromagnetic metal can be used as a method for determining the onset of plasticity and, more important, that of microplasticity, which occurs while the material is in the nominally elastic region.
{"title":"The effect of strain on the a.c. resistance of a metal: a method of studying microplasticity","authors":"A. Esin, W. Jones","doi":"10.1088/0508-3443/18/9/304","DOIUrl":"https://doi.org/10.1088/0508-3443/18/9/304","url":null,"abstract":"The effective a.c. resistance of a conductor is a function of the frequency of the current and the resistivity and the permeability of the conductor. The resistivity and permeability are affected by strain and, by using a suitable high-frequency a.c. bridge, these effects can be amplified and measured as a function of strain. In this paper it is shown that the changes in the effective a.c. resistance which result from straining a ferromagnetic metal can be used as a method for determining the onset of plasticity and, more important, that of microplasticity, which occurs while the material is in the nominally elastic region.","PeriodicalId":9350,"journal":{"name":"British Journal of Applied Physics","volume":"14 1","pages":"1251-1356"},"PeriodicalIF":0.0,"publicationDate":"1967-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76248658","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1967-09-01DOI: 10.1088/0508-3443/18/9/307
D. Craik, R. Lane
The existence of interaction domains in elongated single-domain materials has been confirmed using the Bitter pattern technique. Structural changes were observed on the basal and axial planes of the elongated single-domain materials and compared with the hysteresis loops. In order to explain the form and rearrangement of these domains a new magnetization reversal mechanism is proposed for elongated single-domain particle assemblies, involving lateral interactions during fanning.
{"title":"Magnetization reversal mechanisms in assemblies of elongated single-domain particles","authors":"D. Craik, R. Lane","doi":"10.1088/0508-3443/18/9/307","DOIUrl":"https://doi.org/10.1088/0508-3443/18/9/307","url":null,"abstract":"The existence of interaction domains in elongated single-domain materials has been confirmed using the Bitter pattern technique. Structural changes were observed on the basal and axial planes of the elongated single-domain materials and compared with the hysteresis loops. In order to explain the form and rearrangement of these domains a new magnetization reversal mechanism is proposed for elongated single-domain particle assemblies, involving lateral interactions during fanning.","PeriodicalId":9350,"journal":{"name":"British Journal of Applied Physics","volume":"14 1","pages":"1269"},"PeriodicalIF":0.0,"publicationDate":"1967-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88985997","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1967-09-01DOI: 10.1088/0508-3443/18/9/122
D. Craik
In their 1954 paper Rhodes and Rowlands calculated demagnetizing energies for uniformly magnetized rectangular prismatic crystals and derived effective demagnetizing factors Nb with no reference to the internal fields. It is shown that the demagnetizing field at the centre of a cube is precisely NbIs and that the fields at the centres of rectangular blocks with square cross section lie near to the values of NbIs and NdIs, where Nd is the demagnetizing factor of the inscribed ellipsoid.
{"title":"Demagnetizing fields in uniformly magnetized rectangular prismatic crystals","authors":"D. Craik","doi":"10.1088/0508-3443/18/9/122","DOIUrl":"https://doi.org/10.1088/0508-3443/18/9/122","url":null,"abstract":"In their 1954 paper Rhodes and Rowlands calculated demagnetizing energies for uniformly magnetized rectangular prismatic crystals and derived effective demagnetizing factors Nb with no reference to the internal fields. It is shown that the demagnetizing field at the centre of a cube is precisely NbIs and that the fields at the centres of rectangular blocks with square cross section lie near to the values of NbIs and NdIs, where Nd is the demagnetizing factor of the inscribed ellipsoid.","PeriodicalId":9350,"journal":{"name":"British Journal of Applied Physics","volume":"20 1","pages":"1355-1356"},"PeriodicalIF":0.0,"publicationDate":"1967-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76622215","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1967-09-01DOI: 10.1088/0508-3443/18/9/418
P. L. Worledge, D. White
A controlled method of oxidizing thin films of tantalum and aluminium in a radio-frequency-excited glow discharge is described. The oxide films have been assessed as the dielectric in metal-metal-oxide-metal capacitor structures. Reciprocal capacitance varies linearly with the voltage applied to the metal film in the discharge over the range 0 to 48 v. The process is similar to but less efficient than anodization in a liquid electrolyte. Compared with oxide films formed by liquid anodization the electrical properties are poor, probably because of the more energetic conditions in the discharge.
{"title":"Controlled oxidation of tantalum and aluminium in a radio-frequency-excited glow discharge","authors":"P. L. Worledge, D. White","doi":"10.1088/0508-3443/18/9/418","DOIUrl":"https://doi.org/10.1088/0508-3443/18/9/418","url":null,"abstract":"A controlled method of oxidizing thin films of tantalum and aluminium in a radio-frequency-excited glow discharge is described. The oxide films have been assessed as the dielectric in metal-metal-oxide-metal capacitor structures. Reciprocal capacitance varies linearly with the voltage applied to the metal film in the discharge over the range 0 to 48 v. The process is similar to but less efficient than anodization in a liquid electrolyte. Compared with oxide films formed by liquid anodization the electrical properties are poor, probably because of the more energetic conditions in the discharge.","PeriodicalId":9350,"journal":{"name":"British Journal of Applied Physics","volume":"67 1","pages":"1337-1339"},"PeriodicalIF":0.0,"publicationDate":"1967-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81491662","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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