Shape Of String Research Articles

97/00441 Alkaline fuel cells: A critical view

Improving photovoltaic (PV) system reliability and reducing maintenance and operating costs have become important factors in increasing the competitiveness of the PV energy market. Addressing these issues requires diagnostic methods that can detect and identify the occurrence and cause of power loss in the PV system, be it external, such as shading or soiling of the PV modules; or degradation of the solar cells and balance-of-system components. This allows for performing preventive and/or reparative maintenance, thus minimizing further losses and costs.This article proposes and experimentally demonstrates for the first time a complete diagnostic methodology for PV string inverter systems, which takes advantage of the current–voltage (I–V) measurement capability of the string inverter itself to perform the fault diagnosis. This enables the detection of shading, increased series-resistance losses, and potential-induced degradation affecting the PV string, by analysing changes in its I–V curve.The diagnostic methodology is based on parameters that can be easily calculated from the shape of the PV string’s light I–V curve characteristic, making it machine-analysis friendly and suitable for implementation in the string inverter. Moreover, the dimensionless formulation of the diagnostic parameters and the application of fuzzy logic in evaluating the diagnostic rules, make this method applicable to a wide range of conventional crystalline silicon based PV systems.The design and analysis of the diagnostic parameters and logic was performed based on module-level tests on conventional crystalline silicon PV modules, and were optimized to detect even small partial shading and increase series-resistance losses. To demonstrate the practical application and operation of this method, the diagnostic parameters and rules were applied “as is” to a field test PV system consisting of a crystalline silicon based PV string and a commercial string inverter capable of measuring the I–V curve of the PV string, yielding a similar high-detection rate.

Studies on Fiber and Geometry Using a String Shape Model (Part 3). Analysis of the Relationship between Patterns of Textiles and Information by means of Fractal Images and Dimensions.

Textile fibers have long been used as a medium to record,preserve and transmit information. Jacquard invented Jacquard fabrics with optional patterns that are produced by using punch cards. Punch card corresponds to a pattern with the position of small punched holes. The form of information is regarded as the regular mass of information element or the so-calledsystematized form. There are three patterns in systmatized forms of information elements on textiles. They are linear form,branched form,and grouping form. Gestalists attempted to classfy the types of interaction in the visual system and called them laws of perception. Their lows of grouping includes proximity,similarity,good continuation,and closure. The laws of grouping may be seen in a systematized form of the information element for the spaces in lace. The box-counting dimensions of string part, space part of lace and fractal images were measured to discuss the relationship between box-counting dimension and grouping(law of perception).

Bifurcation of the shape of a rotating string

We study the problem of the shape of an inextensible string rotating in a gravitational field. We discuss a method of solution and present some results: bifurcation diagrams and equilibrium shapes of the string for certain values of the angular velocity ω.

Integrated collapsible guitar, sound studio and case

A collapsible stringed instrument which is integrated into a compact carrying case with a portable sound studio. This instrument is collapsible by sliding the fretboard along channels in the body of the instrument inwardly or toward the rearward face of the case to retract or collapse the instrument for carrying. This instrument is extendible by following the reverse process. A novel, removable multiple coil pickup is included which plays at a normal electric tone or pitch, or at a combined, different tone or pitch by alternately lifting open or lowering to close the hinged top portion thereof. Said portable sound studio has a compact disc (CD) player, cassette tape player/recorder, and a special effects circuitry board for amplifying, mixing and altering sounds. An alternative embodiment of the present invention includes a "Hummingbird" fretboard having frets with ridges cut therein and which ridges generally decrease in size and shape in direct correspondence to guitar string size and shape.

Permeation mechanism of DNA molecules in solution through cuprammonium regenerated cellulose hollow fiber (BMM tm)

We tried to clarify the membrane permeation mechanism of biopolymer DNA molecule in solution through cuprammonium regenerated cellulose hollow fiber (BMM tm) from the dependence of the permeability of the DNA molecule on the molecular weight (MW), the transmembrane pressure ( ΔP), the total challenge dose, the original concentration of DNA and on the conformation of DNA and from the observation of the shape of the DNA molecule remaining in the membrane wall. The shape of the DNA molecule was observed using transmission electron microscopy (TEM). The permeability of DNA molecules decreased with an increase in the MW of the DNA molecule. The MW of the molecule which showed a permeability of more than 0.9 was 1 × 10 6 for the protein with global configuration and 1 × 10 8 for DNA. The linear protein of the blood coagulation factor VIII combined with von Willebrand factor (F-VIII with vWF) with MW of 2 × 10 7 showed a permeability similar to that of DNA rather than that of the global protein. When ΔP decreased, the permeability of DNA decreased. Electron microscope observation showed that the DNA molecules were elongated by the shear stress originated in the flow of the solution in pores. We can conclude that: (1) Protein and DNA permeate through BMM mainly based on sieving effects. (2) The molecules of DNA and F-VIII with vWF are considered to deform into a string shape along the stream line. The chemical structure of a molecule and the shear stress of filtration govern its deformability. The deformation of the molecule contributes to the permeability through BMM. (3) The sieving effect in working on the permeation of molecules should take into account their deformability in addition to their geometrical size.

The Riemann Hypothesis and Inverse Spectral Problems for Fractal Strings

Motivated in part by the first author's work [23] on the Weyl-Berry conjecture for the vibrations of ‘fractal drums’ (that is, ‘drums with fractal boundary’), M. L. Lapidus and C. Pomerance [31] have studied a direct spectral problem for the vibrations of ‘fractal strings’ (that is, one-dimensional ‘fractal drums’) and established in the process some unexpected connections with the Riemann zeta-function ζ = ζ (s) in the ‘critical interval’ 0 < s < 1. In this paper we show, in particular, that the converse of their theorem (suitably interpreted as a natural inverse spectral problem for fractal strings, with boundary of Minkowski fractal dimension D ∈ (0,1)) is not true in the ‘midfractal’ case when D = 1 2 , but that it is true for all other D in the critical interval (0,1) if and only if the Riemann hypothesis is true. We thus obtain a new characterization of the Riemann hypothesis by means of an inverse spectral problem. (Actually, we prove the following stronger result: for a given D ∈ (0,1), the above inverse spectral problem is equivalent to the ‘partial Riemann hypothesis’ for D, according to which ζ = ζ (s) does not have any zero on the vertical line Re s = D.) Therefore, in some very precise sense, our work shows that the question (à la Marc Kac) “Can one hear the shape of a fractal string?” – now interpreted as a suitable converse (namely, the above inverse problem) – is intimately connected with the existence of zeros of ζ = ζ(s) in the critical strip 0 < Res < 1, and hence to the Riemann hypothesis.

Stable and unstable circular strings in inflationary universes.

It was shown by Garriga and Vilenkin that the circular shape of nucleated cosmic strings, of zero loop-energy in de Sitter space, is stable in the sense that the ratio of the mean fluctuation amplitude to the loop radius is constant. This result can be generalized to all expanding strings (of non-zero loop-energy) in de Sitter space. In other curved spacetimes the situation, however, may be different. In this paper we develop a general formalism treating fluctuations around circular strings embedded in arbitrary spatially flat FRW spacetimes. As examples we consider Minkowski space, de Sitter space and power law expanding universes. In the special case of power law inflation we find that in certain cases the fluctuations grow much slower that the radius of the underlying unperturbed circular string. The inflation of the universe thus tends to wash out the fluctuations and to stabilize these strings.

Studies on Geometry Using Fiber and String Shape Model. (Part 1). Plane-Filling Curves Using String-systems and Their Applications to Textile Goods.

The structure of woven and knitted fabrics was analyzed using string-systems; consequently, plane-filling textile goods are proved to be compatible with the Peano curve. The string-systems were devised for a fixed breadth string line model to depict figures computationally by rotational displacement, parallel displacement and scaling based on a basic unit. A novel alternative (substitutive) dimension using the fixed breadth string model was proposed to determine the dimensions of real textile goods. This alternative dimension was termed a practical dimension, which takes a non-integral dimension. The shapes and patterns of textile goods correspond to the self-similar fractal structure, whereas the textile fibers have flexibility at their shape. In the case of the application of fractal dimension to the textile goods, a coefficient was attributed to the soft and limp properties of textile fibers, i.e., a fiber coefficient must be multiplied by the dimension. The coefficient ranges from zero to unity in proportion to the increase of fiber stiffness. A smoothing procedure which utilized two types of approximate curves, namely, the spline function and the model string rotation, was applied to the textile goods models. Furthermore, the string model of free rotation method could explain fiber shape deformation by flexibility.

THE EXTRA GAUGE SYMMETRY OF STRING DEFORMATIONS IN ELECTROMAGNETISM WITH CHARGES AND DIRAC MONOPOLES

We point out that electromagnetism with Dirac magnetic monopoles harbors an extra local gauge invariance called monopole gauge invariance. The gauge transformations act on a gauge field of monopoles [Formula: see text] and are independent of the ordinary electromagnetic gauge invariance. The extra invariance expresses the physical irrelevance of the shape of the Dirac strings attached to the monopoles. The independent nature of the new gauge symmetry is illustrated by comparison with two other systems, superfluids and solids, which are not gauge-invariant from the outset but which nevertheless possess a precise analog of the monopole gauge invariance in their vortex and defect structure, respectively. The extra monopole gauge invariance is shown to be responsible for the Dirac charge quantization condition 2eg/ħc=integer, which can now be proved for any fixed particle orbits, i.e. without invoking fluctuating orbits which would correspond to the standard derivation using Schrödinger wave functions. The only place where quantum physics enters in our theory is by admitting the action to jump by 2πħ×integer without physical consequences when moving the string at fixed particle orbits.

The application of computer software to orebody modelling and evaluation at South Crofty tin mine, Cornwall

Abstract The orebodies at South Crofty take the form of a series of steeply dipping composite fissure-veins/lodes in the classic style of this mining district. Extraction is underground. The tin bearing lodes belong to the ENE-striking series. Cassiterite mineralization is in two main stages characterized by tourmaline and chlorite gangue respectively. The paragenesis and distribution of this mineralization appears related to the structural evolution of a lode, or group of lodes. There are two main groups based on lode composition. The first contains relatively simple veins whose dominant gangue is blue/black tourmaline, and which have limited wall rock alteration. Cassiterite mineralization is associated with a later quartz brecciation of these veins. The second group has a more obviously complex paragenesis with the development of a series of quartz and quartz-haematite phases. Cassiterite mineralization in this group is associated not only with tourmalinite veining, but also with a chlorite-fluorite event. Wall rock alteration, often haematite dominated, is often extensive. In structural terms, both groups of lodes appear to have evolved in a similar manner, initially, with the lodes dividing in an en-echelon style. Division is limited to recognizable zones. Intralode shearing and open space mineralization, however, characterizes only the second group, where the tourmaline element of the lode zone may be lost as a result. The resulting distribution patterns of cassiterite mineralization for these two groups are broadly elliptical when viewed in longitudinal projection. A differing style of orebody is also present. These are zones comprising a series of relatively small flat lying veins together with replacement mineralization, making up steep ‘dipping’ sub-cylindrical bodies. Cassiterite belonging to both tourmaline and chloritic phases is present. These distributions can be successfully modelled by computer. This is essential for grade prediction where information between mined levels is absent. In this example, SURPAC was used, enabling a powerful combination of string modelling techniques, together with a geostatistically produced block model. This last is computed using inverse-distance weighting with ellipsodial search envelopes. Within the lodes, variation in the elliptical pattern is accounted for by modelling of differing trends, followed by extraction from each model using string intersection. The results are then combined into one model in longitudinal projection. Block grades are simply calculated by overlaying the block pattern, as string shapes, with resulting grades. Geological or mining reserves can be calculated using the same method. Further modelling is required for the mineralized zones. This is achieved by using string structures and 3D visualization for sections through the orebody. These are defined from a combination of diamond drilling and interpretation. The use of strings ensures the original data co-ordinates are honoured. A three-dimensional triangulated surface is formed over these cross sections, with interpolation between sections controlled by the geologist. Zones of differing grade within the orebody can be similarly modelled. Volumes are simply calculated. The 3D model may contain proposed or existing underground workings, in addition to the orebody model. The complete model is then sectioned in a chosen orientation. These sections are used to enclose grade data held in a geostatistically calculated block model to complete grade calculations.

INFLATION-DRIVEN STRING INSTABILITIES: TOWARDS A SYSTEMATIC LARGE-R EXPANSION

We present the general structure of a large-R expansion for the evolution of classical strings during a phase of fast inflation together with explicit results for several subleading terms. We are thus able to check the consistency of the expansion and to describe the approach to asymptopia both in terms of string shapes and of their equation of state.

Measuring the size and shape of strings

We define size and shape in terms of observables, i.e. scattering amplitudes. Excited strings can be measured by scattering ground-state string probes off them. We pick an example where, classically, the ends of the string trace out a circle. Our calculation shows that the radius of the circle is proportional to the mass of the string, M, in agreement with classical expectations. However, on distance scales less than √In M, quantum fluctuations are important and a classical space-time picture becomes questionable.

Configurational statistics of strings, fractals and polymer physics

We study the statistical properties of a network of strings on a torus. The region of very long strings is accessible and two different phases are found (short and long strings) with different statistical behaviour. The “new” very long string phase shows a non-trivial structure. By a direct comparison between a string network and a system of polymers, we interpret the new scaling law as a result of cooperative phenomena pointing out the presence of string-string and long-range correlations. The former correlations are coming from a screening phenomenon while the latter from a gyration radius analysis of the string shape. Non-trivial topological classes of strings contribute very differently to the global scaling results. We study fractality and the brownian shape of strings as possible characteristics properties of the system distinguishing among the several string topologies.

レーザレオロジープロセシングに関する研究 Ｉ 熱的加工現象の基礎研究

Laser Rheology Processing is the process which can produce near net shape parts by irradiating laser onto string shape material which is composed of powder and liquid binder and extruded onto the table or part processed before. Liquid binder is evaporated instantly after laser is irradiated. This report deals with the fundamental research on thermal phenomena in process. It is found that in case of Fe powder the surface layer of the processed part is oxidized under the atmosphere and most heat is hindered to flow through it. So it is recommended that the process is done without the existence of O2. It is also found that the process is better done in a little lower range of temperature from the melting point of the powder material.

Renormalization of string functionals

We investigate analytic renormalization procedures for functional integrals, corresponding to field theories defined on compact manifolds, which arise, e.g., from string functionals of the Nambu-Schild-Eguchi type. Although these models belong to the nonrenormalizable class of quantum field theories, we prove finiteness for a rectangular string shape up to three-loop level, for circular boundary up to two-loop order, and for a variety of graphs in higher order, thus indicating that the result might hold in general. From the explicit calculation of the two-loop approximation we extract the first model-dependent corrections to the $q\overline{q}$ potential or the Casimir effect. The importance of dilation transformations for the properties of the renormalization procedure are investigated. We prove that under certain conditions, forced by symmetry properties, the association of finite values to divergent series is unique, independent of the regularization procedure.

On the Shape of a Random String

We define a string of length $m$ to be a sequence $z_0, z_1,\cdots, z_m$ of points in $Z^2$ which are chosen so that $z_{i-1}$ and $z_i$ are adjacent points on the lattice. If we consider the set of all strings from $z_0 = (0, 0)$ to $z_m = (n, 0)$ then we can introduce a probability distribution by assuming that all the strings are equally likely. In this paper we will prove some results which describe the shape of the random string when $m/n\rightarrow \lambda \in (1, \infty)$. The main result states that if we let $(U_k, V_k)$ be the coordinate of $z_k$ then $(U_{\lbrack m\cdot \rbrack}/n, V_{\lbrack m\cdot \rbrack}/n^{\frac{1}{2}})$ converges weakly to $(\cdot, \rho^{\frac{1}{2}}W_0(\cdot))$ where $W_0$ is a Brownian bridge and $\rho = (\lambda^2 - 1)/2\lambda$. A second set of results describes $B_n = \sup\{U_k - U_l: 0 \leqslant k \leqslant l \leqslant m\}$, a quantity which measures the amount of backtracking in the string. We find that this is $0(\log n)$ and there is a sequence of constants $b_n$ so that $B_n - b_n$ approaches a double exponential distribution. The results described above were motivated by, and are related to, results of Abraham and Reed, and Gallovotti on the shape of the interface profile in the two dimensional Ising model.

Evidence for Dislocation Reactions in White Tin Single Crystals

Evidence for Dislocation Reactions in White Tin Single Crystals

On the motion of the bowed violin string

Oscillations with nodes at the bow point have been observed. For a typical violin string such oscillations exist for β &amp;gt; 0.08 (here β is the relative bow position along the string). For β &amp;gt; 0.18 the amplitude of this motion may become comparable to the Helmholtz motion if the bow force exceeds a critical value (2–40 g/wt. depending on the value of β). At the critical force and with β ≠ n−1 (n = 2, 3, 4...), the waveform can be well described analytically. The analytic expression consists of two terms, a sinusoid and the usual Helmholtz expression. It is used to calculate consecutive string shapes. At the critical bow force, the slip period of the string at the bow point is observably reduced to half the value given by the classical Helmholtz theory. However, this slip duration is given by the analytic expression. For bow forces much larger than the critical value the sinusoids of the waveforms (including the slip duration at the bow point) become narrower than the “predictions.” It is shown that this type of motion does not exist for β &amp;lt; 0.18 because it demands too high a bow force. The relationship between this motion and Raman's “higher types of motion” will be explained.

The Creative Use of Multimedia (or the Shape of Strings to Come)

The Creative Use of Multimedia (or the Shape of Strings to Come)

On the equilibrium shape and tension of a flexible string acted upon by external forces that are functions of the orientation of the string in space

On the equilibrium shape and tension of a flexible string acted upon by external forces that are functions of the orientation of the string in space