Analytic mode matching for a circular dissipative silencer containing mean flow and a perforated pipe

An analytic mode matching scheme that includes higher order modes is developed for a straight-through circular dissipative silencer. Uniform mean flow is added to the central airway and a concentric perforated screen separates the mean flow from a bulk reacting porous material. Transmission loss predictions are compared with experimental measurements and good agreement is demonstrated for three different silencers. Furthermore, it is demonstrated that, when mean flow is present, the axial kinematic matching condition should equate to that chosen for the radial kinematic boundary condition over the interface between the airway and the material. Accordingly, if the radial matching conditions are continuity of pressure and displacement, then the axial matching conditions should also be continuity of pressure and displacement, rather than pressure and velocity as previously thought. When a perforated screen is present the radial pressure condition changes, but the radial kinematic condition should always remain equivalent to that chosen for the axial kinematic matching condition; here, results indicate that continuity of displacement should be retained when a perforated screen is present

Measuring the information content of customer foreign exchange orders

This paper investigates whether customer order flow conveys information about future foreign exchange (FX) prices. We use a unique data set from a leading Australian commercial bank that records every FX trade made by the bank in the spot Australian dollar/US dollar market between 2005 and 2010. We find little evidence in support of a cointegrating relation or a statistically significant correlation between customer order flow and FX returns. However, consistent with the liquidity provision role of non-financial customers in Evans and Lyons ((2002) Order flow and exchange rate dynamics. Journal of Political Economy 110: 170–180), we find a statistically significant negative correlation between order flow from the diversified economic sector and FX returns. A dynamic analysis suggests that order flow has little or no price impact on FX returns. These results suggest that the non-financial customer order flow of a commercial bank does not carry information about FX prices

From Large to Small Scales: Global Models of the ISM

We review large scale modelling of the ISM with emphasis on the importance to include the disk-halo-disk duty cycle and to use a dynamical refinement of the grid (in regions where steep variations of density and pressure occur) for a realistic modelling of the ISM. We also discuss the necessity of convergence of the simulation results by comparing 0.625, 1.25 and 2.5 pc resolution simulations and show that a minimum grid resolution of 1.25 pc is required for quantitatively reliable results, as there is a rapid convergence for Delta x \leq 1.1 pc.Comment: 10 pages, 8 figures that include 2 simulation images (in jpeg format) and 6 plots (4 in ps and 2 in jpeg formats), to appear in the proceedings of ``From Observations to Self-Consistent Modelling of the ISM in Galaxies'', Kluwe

An integrality theorem of Grosshans over arbitrary base ring

We revisit a theorem of Grosshans and show that it holds over arbitrary commutative base ring $k$. One considers a split reductive group scheme $G$ acting on a $k$-algebra $A$ and leaving invariant a subalgebra $R$. If $R^U=A^U$ then the conclusion is that $A$ is integral over $R$.Comment: 5 pages; final versio

RANCANG BANGUN KRAN WUDHU OTOMATIS MENGGUNAKAN LDR(LIGHT DEPENDENT RESISTOR)

RANCANG BANGUN KRAN WUDHU OTOMATIS MENGGUNAKAN LDR (LIGHT DEPENDENT RESISTOR)FAHRISAN FD1304005010044ABSTRAKBerkembangnya teknologi mendorong manusia untuk melakukan sesuatu dengan lebih cepat dan praktis, salah satunya adalah teknologi yang dapat dimanfaatkan untuk mempermudah pekerjaan manusia dan lebih efesien, baik dalam hal waktu, tenaga biaya dan lain-lain. Teknologi tersebut membantu pekerjaan manusia secara mudah dan otomatis. Salah satunya perancangan kran wudhu otomatis. Masalah yang sering timbul dalam proses pengambilan wudhu seringkali mengalami kelupaan pada saat menutup kran setelah selesai berwudhu, sehingga air terus menetes dan mengakibatkan pemborosan. Maka oleh karena itu solusi yang ditawarkan adalah dengan pembuatan sistem kran otomatis. Pengguna tidak perlu lagi untuk membuka tutup tuas kran air, dikarenakan system ini menggunakan sensor LDR yang mana jika sinar laser yang dipancarkan ke LDR terhalang maka rangkaian akan aktif dan kran akan terbuka otomatis. Dengan menerapkan metode kran air otomatis ini dapat diketahui bahwa metode ini dapat diterapkan untuk menciptakan otomatisasi pada kran dan juga penghematan air. Dengan begitu air tidak banyak terbuang yang menimbulkan pemborosan.Kata kunci : LDR, Relay, Selonoid valve atau Pomp

Deligne categories and reduced Kronecker coefficients

The Kronecker coefficients are the structural constants for the tensor categories of representations of the symmetric groups, namely, given three partitions λ,μ,τ of n, the multiplicity of λ in μ⊗τ is called the Kronecker coefficient g[superscript λ][subscript μ,τ]. When the first part of each of the partitions is taken to be very large (the remaining parts being fixed), the values of the appropriate Kronecker coefficients stabilize; the stable value is called the reduced (or stable) Kronecker coefficient. These coefficients also generalize the Littlewood–Richardson coefficients and have been studied quite extensively. In this paper, we show that reduced Kronecker coefficients appear naturally as structure constants of Deligne categories [bar under Rep](S[subscript t]). This allows us to interpret various properties of the reduced Kronecker coefficients as categorical properties of Deligne categories [bar under Rep](S[subscript t]) and derive new combinatorial identities

Spectral analysis of nonsymmetric quasi-toeplitz matrices with applications to preconditioned multistep formulas

The eigenvalue spectrum of a class of nonsymmetric preconditioned matrices arising in time-dependent partial differential equations is analyzed and discussed. The matrices generated by the underlying numerical integrators are small rank perturbations of block Toeplitz matrices; circulant-like preconditioners based on the former are considered. The eigenvalue distribution of the preconditioned matrix influences often crucially the convergence of Krylov iterative accelerators. Due to several reasons (lack of symmetry, band structure, and coefficients depending on the size) the classical approach based on smooth generating functions gives very little insight here. Therefore, to characterize the eigenvalues, a difference equation approach exploiting the band Toeplitz and circulant patterns generalizing the well-known results of Trench is proposed