bluuebunny/crossref_metadata_2025 huggingface dataset:
An alternative method for determining the coefficient of thermal expansion of composite material of spherical particles
Authors: Duc Nguyen Dinh , Tung Hoang Van , Hang Do Thanh
Published: December 2014

Composite material is widely used in modern structures. Many researchers have been involved in studying, developing and applying this kind of material. The composite material of spherical particles is a material composed of continuous matrix phase and spherical particles. In modern technique, it is very necessary to consider the influence of temperature on toughness and stability of structures. Therefore, determining the coefficient of thermal expansion of composite as a function of the coefficients and volume fractions of matrix and particle phases is a practical requirement. In this paper. we would like to introduce an alternative derivation method in order to obtain the thermal expansion coefficient of two-phase composite of spherical particles. Our results are the same as Vanin's and other authors'.
Influence of trajectories on the joint torques of kinematically redundant manipulators
Authors: Khang Nguyen Van , Tuan Do Anh , Dien Nguyen Phong , Nam Tran Hoang
Published: December 2014

This paper presents an algorithm for solving the inverse dynamics problem of redundant manipulators using MAPLE software. The method has the advantage of generating efficient symbolic solutions which reduces the computational cost. The influence of trajectories on the joint torques of redundant manipulators is considered. The theory is illustrated by the numerical simulation of a redundant four-link planar manipulator.
Về dao động của hệ gần với hệ phi tuyến mạnh
Authors: Dao Nguyen Van
Published: December 2014

Special Issue Dedicated to the Memory of Prof. Nguyen Van Dao
A Cauchy like problem in plane elasticity
Authors: Ang Dang Dinh , Dung Nguyen
Published: December 2014

Let \(\Omega \) be a bounded domain in the plane, representing an elastic body. Let \(\Gamma_0 \) be a portion of the boundary \(\Gamma\) of \(\Omega \), \(\Gamma_0 \) being assumed to be paralled to the \(x\)-axis. It is proposed to determine the stress field in \(\Omega \) from the displacements and surface stresses given on \(\Gamma_0 \). Under the assumption of plane stress, it is shown that \(u_x + u_y\) is a harmonic function. An Airy stress function is introduced, from which the stress field is computed.
Non-linear dynamical analysis of laminated reinforced composite doubly curved shallow shells
Authors: Bich Dao Huy , Long Vu Do
Published: December 2014

The present paper deals with a non-linear dynamical analysis of laminated reinforced composite doubly curved shallow shells. The motion equations of shell based upon the thin shell theory considering the geometrical non-linearity and the Lekhnitsky's smeared stiffeners technique. Simultaneous ordinary differential equations are obtained by means of Bubnov-Galerkin's procedure. Non-linear responses are calculated by using an iterative procedure in conjunction with Newmark constant acceleration scheme. Obtained results allow to discover the influence of stiffeners, the shell geometry on the non-linear response of eccentrically stiffened laminated composite shells.
A note on the Melnikov function
Authors: Dinh Nguyen Van
Published: December 2014

With one (Poincaré section) parameter and a particular motion law (that associated to certain determined point of horno-heteroclinic orbits), the usual form of the Melnikov function seems to be not convenient for certain problems. Another favorable form can be obtained by using a supplementary parameter - the arbitrary time constant in the general mentioned motion law.
Intermittent gaslift flows in vertical pipes
Authors: Hai Duong Ngoc , Khang Nguyen Thuc , Thien Nguyen Duy
Published: December 2014

The paper presents the study results of intermittent gaslift. vertical flows using both experiment and theoretical models. To study the influence of medium thermophysical characteristics on the process efficiency, two gas-liquid systems are used in the experiments. The obtained results show that there is a critical gas injection volume, less than that the liquid slug cannot reach the top of the tubing. Correlations for prediction of liquid entrainment in gas core are also shown for two presented gas-liquid systems. Amodified dynamical model was developed. The model consists of a system of differential equations. The resulting system of equations is numerically solved. The numerical code is verified by using experimental data and calculation data of the other authors. Finally, the effects of system parameters are studied.
Automatic limit and shakedown analysis of 3-D steel frames
Authors: Hung Nguyen Dang , Long Hoang Van
Published: December 2014

This paper presents an efficient algorithm for both limit and shakedown analysis of 3-D steel frames by kinematical method using linear programming technique. Several features in the application of linear programming for rigid-plastic analysis of three-dimensional steel frames are discussed, as: change of the variables, automatic choice of the initial basic matrix for the simplex algorithm, direct calculation of the dual variables by primal-dual technique. Some numerical examples are presented to demonstrate the robustness, efficiency of the proposed technique and computer program.
Preliminary results of the study on the reasons of the Hai Hau erosion phenomenon
Authors: Ninh Pham Van , Vinh Phan Ngoc , Hung Nguyen Manh , Manh Dinh Van
Published: December 2014

Overall the evolution process of the Red River Delta based on the maps and historical data resulted in a fact that before the 20th century all the Nam Dinh coastline was attributed to accumulation. Then started the erosion process at Xuan Thuydistrict and from the period of 1935 - 1965 the most severe erosion was contributed in the stretch from Ha Lan to Hai Trieu, 1965 - 1990 in Hai Chinh - Hai Hoa, 1990 - 2005 in the middle part of Hai Chinh - Hai Thinh (Hai Hau district). The adjoining stretches were suffered from not severe erosion. At the same time, the Ba Lat mouth is advanced to the sea and to the North and South direction by the time with a very high rate.The first task of the mathematical modeling of coastal line evolution of Hai Hau is to evaluate this important historical marked periods e. g. to model the coastal line at the periods before 1900, 1935 - 1965; 1965 - 1990; 1990 - 2005. The tasks is very complicated and time and working labors consuming.In the paper, the primarily results of the above mentioned simulations (as waves, currents, sediments transports and bottom - coastal lines evolution) has been shown. Based on the obtained results, there is a strong correlation between the protrusion magnitude and the southward moving of the erosion areas.
On a feedback-feedforward identification control algorithm for feedback active controlled structures
Authors: Viet La Duc , Anh Nguyen Dong
Published: December 2014

Linear quadratic regulator (LQR) is an effective method of feedback active control theory. However, the LQR control is not truly optimal because it is only a feedback algorithm, i.e. the external excitation term is ignored in the optimal equation. In a previous paper [1], the identification algorithm is presented for feedback active controlled systems to identify the excitation from the structural response measured. The aim of this paper is to propose a feedback-feedforward control algorithm using the identified excitation to improve the classical LQR control. A numerical simulation is applied to an eight story building subjected to base acceleration and controlled by active mass damper system.
Research on aerodynamics of a wing-in-surface-effect ship by theory and experiment
Authors: Tang Pham Xuan , Thang Ngo Tri , Uy Pham Vu , Hai Duong Ngoc
Published: December 2014

The paper presents the results of theoretical and experimental studies of the aerodynamic characteristics of a wing-in-surface-effect ship (WISES), which was made under coordination of the Institute of Mechanics, Vietnamese Academy of Science and Technology. The theoretical researches are carried out by the half analytical method and together by the linear and nonlinear vortex lattice methods. The experiment was conducted by the model on wind tunnel OTl of The Technical Institute of Air Force - Air Defense.
Construction, verification of a software for the 2D dam-break flow and some its applications
Authors: Lai Hoang Van , Don Nguyen Thanh
Published: December 2014

In this paper the numerical method for the shallow water equations is studied. The paper consists of 3 sections. In the section 1 the theoretical basis and software IMECI-L2DBREAK for simulation of the 2D dam-break or dyke-break flows is outlined. In the section 2 some results in verification of the IMECH_2DBREAK by the test cases proposed in the big European Hydraulics Laboratories are shown. In the last section some applications of IMECH_2DBREAK for the inundation problem in the Red river delta in the Northern of Vietnam are presented.
Non-linear vibration of eccentrically stiffened laminated composite shells
Authors: Bich Dao Huy , Long Vu Do
Published: December 2014

The present paper deals with a non-linear vibration of eccentrically stiffened laminated composite doubly curved shallow shells. The calculations of internal forces and displacements of the shell are based upon the thin shell theory considering the geometrical non-linearity and the Lekhnitsky's smeared stiffeners technique. From the deformation compatibility equation and the motion equation a system of partial differential equations for stress function and deflection of shell is obtained. The Bubnov-Galerkin's method and iterative procedure in conjunction with Newmark constant acceleration scheme are used for dynamical analysis of shells to give the frequency-amplitude relation of free nonlinear vibration and non-linear transient responses. Numerical results show the influence of boundary conditions and Gauss curvature on the non-linear vibration of shells.
Experimental results of gaslift process
Authors: Hai Duong Ngoc , Thien Nguyen Duy , Canh Nguyen Van
Published: December 2014

In the paper, the investigation results of periodical gas-lift flows in vertical pipes using experiment method are presented. The experiment facilities consist of flow measurement equipment, gas and fluid supplier facilities, tubing system. To study the influence of medium physical and dynamical characteristics on the process efficiency, two liquid-gas systems are used, namely, water-air and spindle oil-air. The objects of investigation are to obtain data from tests conducted in some conduits and to analyse the influence of system physical, geometrical and etc. parameters such as: initial liquid height in the conduits, gas injected volume, conduit diameter, conduit configuration and etc. on the considered process.
Analysis of stiffened laminated composite plates by finite element based on higher-order displacement theory
Authors: Thinh Tran Ich , Quoc Tran Huu
Published: December 2014

In this paper, authors use a finite element model based on higher-order displacement plate theory for analysis of stiffened laminated composite plates. Transverse shear deformation is included in the formulation making the model applicable for both moderately thick and thin composite plates. The plate element used is a nine-noded isoparametric one with nine degrees of freedom at each node. The stiffness of stiffener is reflected at all nine nodes of plate element in which it is placed. Accordingly, the stiffeners can be positioned anywhere within the place element. Free vibration and deflection of stiffened laminated composite plates are carried out, and results are compared with existing analytical and other solutions.
Crack analysis for some structures subjected to thermal and dynamic loads
Authors: Nhu Ngo Huong
Published: December 2014

Numerical methods of crack analysis for some 2D-elasticity problems with thermal and dynamic loads are considered in this work. The general steps of the algorithm are presented. Some programs are written by Gibian languages in the codes Castem for crack analysis of different structures. Numerical illustrations are realized for the crack dam model, the plate with one and two cracks the plate with crack at the hole subjected to under variable tension of thermal loads. The influence of the temperature, dynamic loads or position of the crack on fracture parameters for these structures are investigated. The given programs may be useful for estimating the failure of dams, tunnels or other structures.
Thermal buckling of imperfect functionally graded cylindrical shells according to Wan-Donnell model
Authors: Tung Hoang Van , Duc Nguyen Dinh
Published: December 2014

A thermal buckling analysis of imperfect circular cylindrical shells of functionally graded material is considered. The material properties are assumed varying as a power form of thickness coordinate variable. The Donnell equilibrium and stability equations are considered and the Wan-Donnell model for initial geometrical imperfection is adopted. The thermal loads include the uniform temperature rise and nonlinear temperature change across the thickness of shell. A closed form solution for the thermal buckling of simply supported cylindrical FG shell under the described thermal loads is obtained. The influences of the relative thickness, the imperfection size and the power law index on buckling thermal loads are all discussed.
Slip-shakedown analysis and the assumption of small coupling in frictional contact
Authors: Antoni Nicolas , Son Nguyen Quoc
Published: December 2014

In the frictional contact of solids under cyclic loads, the shakedown behaviour of the relative displacement is of interest in the same spirit as the plastic deformation in plasticity. Cumulative slips may lead to the failure due to large relative displacements of the components of an assembly while cyclic slips are often undesired because of wear and fretting÷fatigue problems. Under Coulomb friction, it is well known that Melan and Koiter theorems are generally not available, except in certain particular cases. In this discussion, the particular case of small coupling between the contact pressures and the slip-displacements is considered. This assumption means that the tangent displacements have small or no influence on the contact pressures which can be then computed from the elastic response as in the uncoupling case. The pressure is thus a given time-dependent function and the Coulomb criterion is reduced to a Mises-like standard law of friction. It is shown here that Melan and Koiter theorems can be applied again as in standard plasticity. The dependence of the yield limit on the loading amplitude is however not classical and the extension of the static and kinematic approaches is discussed to obtain the critical shakedown load or the limit load. The validity of the assumption of small coupling is also explored by numerical simulation in a practical example.
On the solutions of the Mathieu’s equation
Authors: Bich Dao Huy , Bich Nguyen Dang , Tuan Nguyen Anh
Published: December 2014

As shown in [1] solutions of the Mathieu’s equation were classified on three fundamental kinds depending mainly on its parameters. These solutions were constructed in the form of infinite series. This paper presents a new approach in which approximated analytical solutions of the Mathieu’s equation are constructed in the finite form. Depending on parameters of Mathieu’s equations general solutions may obtain following behaviors: either bounded almost periodic, or infinitely increased combining with infinitely decreased and or infinitely increased combining with periodic.
An interesting material that appears to be fit to possibly all future mechanical vibration textbooks
Authors: Elishakoff Isaac
Published: December 2014

A material is suggested for future mechanical vibration textbooks. Both mathematically and conceptually it is simpler than most of the material that is already included in the existing textbooks. It pertains to the inverse vibration problem for inhomogeneous beam, i.e. the beam with the modulus of elasticity that varies along the axial coordinate. Specifically, the solution of the following problem is presented: Find a distribution of the modulus of elasticity of an inhomogeneous beam such that the beam would possess the preselected simple, polynomial vibration mode shape.
Nonlinear dynamics of pipeline with liquid in a vicinity of critical flow velocities
Authors: Limarchenko O. , Vasilevskiy Yu.
Published: December 2014

We developed the nonlinear model of pipeline dynamics with high-speed liquid motion. On the basis of the variational methods we constructed the nonlinear discrete model and numerical algorithm for investigation of problems of dynamics and dynamical stability of pipeline. We considered examples of dynamical behavior of the system for different velocities of liquid flowing, including the case of critical velocity of flow, when loss of straight line stability of pipeline is possible.
Shear strengthening of reinforced concrete beams using epoxy bonded steel plates, CFRP sheets and externally anchored stirrups
Authors: Minh Ha , Mutsuyoshi Hiroshi
Published: December 2014

This research presents the effectiveness of different shear strengthening methods using epoxy bonded steel plates, steel strips, carbon fiber reinforced plastics (CFRP) sheets and externally anchored stirrups for enhancing the shear strength of RC beams. In this study, an experimental program including two series of twelve specimens was carried out to investigate the behavior of RC beams strengthened with the above methods. Further, a numerical analysis using finite element method (FEM) was performed to simulate the behavior of strengthened beams. The effectiveness of using epoxy bonded steel plates, CFRP sheets and externally anchored stirrups for shear strengthening of RC beams is confirmed through both numerical and experimental results.
Stability of non-localized responses for damaging materials
Authors: Pham K. , Marigo J. J.
Published: December 2014

This work is devoted to the analysis of the stability of the homogeneous states of a bar made of a brittle strain softening material submitted to a tensile loading. We distinguish two types of damage models: local damage models and gradient damage models. We show that a local damage model necessarily leads to the unstability of the homogeneous response once the first damage threshold is reached. On the contrary, in the case of a gradient damage model, viewed as a regularization of the underlying local model, the homogeneous damage states of “sufficiently small" bars are stable.
On the design of an optimum active mass-spring-inverted pendulum dynamic vibration absorber for the inverted pendulum type structure
Authors: Sang Nguyen Chi , Thang Nguyen Cao
Published: December 2014

A Dynamic Vibration Absorber (DVA) is appropriate equipment for vibration control in many kinds of engineering. In general, there are two main types of DVAs: the passive DVAs and the active DVAs. The paper presents a design of an active mass-spring-inverted pendulum DVA for the inverted pendulum type structure in case the external force is white noise process. The design is based on the optimum passive DVA as carried out in [4] and apply the optimum control force by minimizing the performance index. Numerical simulation which is done for an inverted pendulum structure in the ocean in three cases without DVA, with passive DVA, with active DVA shows that the active DVA is better than the passive one.
Stationary values of the transmission ratio of the planar fourbar
Authors: Wittenburg J.
Published: December 2014

The transmission ratio of the planar fourbar, i.e. the ratio of the angular velocities of input link and output link, is a function of the input angle. Freudenstein [1] showed how to calculate stationary values of the transmission ratio. In the present paper a new method is described. Like Freudenstein’s method it results in a sixth-order polynomial equation.
Asymptotic expansion of the dispersion equation of Lamb waves in periodically layered elastic media
Authors: Tu Bui Thanh , Vinh Pham Chi , Linh Nguyen Thi Khanh
Published: December 2014

The present paper deals with the problem on Lamb waves propagation in periodically layered, compressible elastic media with initial deformations, in the case of long wavelength approximation (i.e. E = k.h < < 1, where k is the wave number, h is the thickness of one periodicity cell). With the assumption that E < < 1, the dispersion equation is written as: 2 = 2 = [h + c!"h + c2D3 + ... = L cmDm+l·m=0. The main aim of this paper is to find formulae for determining the coefficients Di, ( i 2'. 1). In particular, we prove that D2n = 0 (n 2'. 1), derive formulae for D1 , D3, and construct recurrent formulae for D2n+i (n 2'. 2). Based on these formulae, the solution with any order of accuracy can be obtained. This research is an extension of the investigation by Norris and Santosa [Norris A. and Santosa F., Wave Motion 16 (1992), 33-55] from SH waves (one-component waves) to Lamb waves (two-component waves).
On shakedown and ratchetting of conforming frictional systems
Authors: Ciavarella M.
Published: December 2014

Conforming contact is found on many important areas: materials with cracks, inclusions, layered structures, pinned geometries, etc. Coulomb friction is non-associative i.e. does not satisfy Drucker’s postulates for stability in plasticity theory, and this does not permit to use the classical Melan and Koiter theorems for cyclic loading which however remain obvious necessary conditions. On the other hand, the Coulomb friction cone has a peculiarity, its linear self-similarity, and this permits few general results, quite different but also powerful. For example, we show that for conforming contact, the Bree interaction diagram is open and sectors-shaped, and therefore there is no lower and upper bounds as in plasticity, since there is linear dependence on a load parameter \(\lambda\), and not a limit on \(\lambda\). As there is dependence on initial conditions in general, the Bree diagram doesn’t have the same profound meaning as in plasticity, since multiple steady states are possible. However, there is a complete scaling of the possible states (elastic shakedown, cyclic slip, ratchetting) with load factor \(\lambda\), and hence a worst-scenario can be defined. However, in order to develop residual stresses (which generally will take many cycles of steady cyclic loading), the load cannot go to zero, at least for friction coefficient below the critical value for "wedging". More in general, there needs to be a "permanent stick region" in the steady state.Almost conforming contacts, and in particular, in the case of initial interference, loose the independence on \(\lambda\) at low \(\lambda\) only, but "gain" greater possibilities to develop residual stresses. However, their study can be greatly simplified by developing a master curve approach to study the dependence on \(\lambda\). The theorems can also be considered the extension to cyclic loadings of the Dundurs results for conforming contacts under monotonic loading, in which case the contact area doesn’t vary in time and hence the problem is linear (from which the denomination "receding contacts"). However, here the problems remain fully non-linear, and the contact are not in general receding, nor there is a unique steady state, not even in the case of proportional loading. In the latter case it is nevertheless possible to derive some special results.
A new prismatic solid-shell element ‘SHB6’: Assumed-strain formulation and evaluation on benchmark problems
Authors: Trinh Vuong Dieu , Abed-Meraim Farid , Combescure Alain
Published: December 2014

In this paper, the formulation of a new six-node solid–shell element denoted (SHB6) is proposed. This prismatic element is based on a purely three-dimensional approach, and hence has displacements as the only degrees of freedom. A reduced integration scheme is adopted consisting of one-point in-plane quadrature and an arbitrary number of integration points, with a minimum number of two, distributed along the ‘thickness’ direction. Moreover, in order to enhance its performance and to greatly reduce most locking effects, specific projections are introduced based on the assumed-strain method. The resulting derivation can then be used to model thin structural problems, while taking into account the various through-thickness phenomena. A careful analysis of potential stiffness matrix rank deficiencies reveals that no hourglass modes need to be controlled. However, without assumed-strain method, the element exhibits some shear and thickness-type locking, which is common in linear triangular elements associated with constant strain states. After the formulation of the element is detailed, its performance is assessed through a set of representative benchmark problems illustrating its capabilities in various situations. More specifically, this prismatic solid–shell element proves to be an essential complement to the SHB8PS hexahedral element in meshing arbitrarily complex geometries.
Transient analysis of laminated composite plates using NURBS-based isogeometric analysis
Authors: Nguyen Lieu B. , Thai Chien H. , Dang Ngon T. , Nguyen-Xuan H.
Published: December 2014

We further study isogeometric approach for response analysis of laminated composite plates using the higher-order shear deformation theory. The present theory is derived from the classical plate theory (CPT) and the shear stress free surface conditions are naturally satisfied. Therefore, shear correction factors are not required. Galerkin weak form of response analysis model for laminated composite plates is used to obtain the discrete system of equations. It can be solved by isogeometric approach based on the non-uniform rational B-splines (NURBS) basic functions. Some numerical examples of the laminated composite plates under various dynamic loads, fiber orientations and lay-up numbers are provided. The accuracy and reliability of the proposed method is verified by comparing with analytical solutions, numerical solutions and results from Ansys software.
Nonlinear post-buckling of thin FGM annular spherical shells under mechanical loads and resting on elastic foundations
Authors: Duc Nguyen Dinh , Anh Vu Thi Thuy , Bich Dao Huy
Published: December 2014

This paper presents an analytical approach to investigate the nonlinear buckling and post-buckling of thin annular spherical shells made of functionally graded materials (FGM) and subjected to mechanical load and resting on Winkler-Pasternak type elastic foundations. Material properties are graded in the thickness direction according to a simple power law distribution in terms of the volume fractions of constituents. Equilibrium and compatibility equations for annular spherical shells are derived by using the classical thin shell theory in terms of the shell deflection and the stress function. Approximate analytical solutions are assumed to satisfy simply supported boundary conditions and Galerkin method is applied to obtain closed-form of load-deflection paths. An analysis is carried out to show the effects of material and geometrical properties and combination of loads on the stability of the annular spherical shells.
Gerencia Estratégica E Innovación Empresarial: Referentes Conceptuales
Authors: González Molano Carlos , Martínez Campo José Luis
Published: December 2014

La innovación se ha convertido en uno de los instrumentos fundamentales dentro de las empresas que quieren seguirsiendo competitivas y además socialmente responsables, en un entorno cada vez más complejo y cambiante. Contodo, la innovación no es un concepto fácil de entender; muchas empresas, e incluso académicos, todavía desconocensu significado y cómo puede afectar su evolución. Así mismo, la innovación no siempre implica crear algo nuevo,sino que a veces está relacionada con implementar algo que ya existe. No obstante, muchas firmas abusan de estadefinición básica; todo lo que es nuevo para ellos, por pequeño que sea, lo llaman innovación; confundiéndose enmuchos casos la innovación con mejora continua. Este artículo busca lograr una aproximación entre la gerenciaestratégica y la innovación empresarial, desde una perspectiva de la evolución conceptual de estos constructos.
Effects of Integrating Mowing and Imazapyr Application on African Rue (Peganum harmala) and Native Perennial Grasses
Authors: Johnson Dustin D. , Davies Kirk W.
Published: December 2014

African rue is a poisonous, perennial forb that readily invades salt-desert shrub and sagebrush-steppe rangelands. Information detailing options for integrated management of African rue is lacking. To date, a few studies have researched the efficacy of different herbicides for controlling African rue, but none have investigated integrated approaches to its management. Broadcast applications of imazapyr at three rates (0.275, 0.55, and 0.85 kg ae ha−1) were made, with and without a prior mowing treatment, to African rue when it was in full bloom. Imazapyr resulted in significant reductions in both the cover and density of African rue, regardless of application rate or mowing treatment (P < 0.05). Mowing had no effect on African rue cover or density (P > 0.05). Higher rates of imazapyr resulted in significant reductions in the cover of native perennial bunchgrasses (P < 0.05), whereas the low rate did not affect perennial grass cover, regardless of mowing treatment (P > 0.05). Integrating a mowing treatment with imazapyr applications was less effective for controlling African rue than applying herbicide alone. Mowing before imazapyr application did not increase survival of perennial grasses. Our results suggest that the recommended rate of imazapyr for controlling African rue (0.85 kg ae ha−1) could be reduced by as much as one-third on dry floodplain ecological sites within the northern Great Basin without comprising its effectiveness for controlling African rue. This lower rate would reduce nontarget damage to native perennial grasses, which are the dominant functional group in the herbaceous understory. Less damage to native perennial grasses would probably accelerate understory recovery and help prevent invasion by other invasive species.
Effects of Aminocyclopyrachlor Herbicide on Downy Brome (Bromus tectorum) Seed Production under Field Conditions
Authors: Ball Daniel A.
Published: December 2014

Previous research has shown that pyridine growth regulator herbicides can affect seed production in annual grasses including downy brome, Japanese brome, wheat, and other cereal grain crops. Aminocyclopyrachlor is a pyridine carboxylic acid growth regulator herbicide that has recently been registered for broadleaf weed and brush control in nonagricultural areas, which may help facilitate release of native perennial grasses in native plant restoration sites. The influence of aminocyclopyrachlor on downy brome seed production was evaluated at multiple application rates and timings under controlled field conditions. The effect of aminocyclopyrachlor on seed production was compared with aminopyralid, another pyridine growth regulator herbicide. When applied to downy brome plants in the early vegetative stage (EPOST) at approximately 580 growing degree days (GDD), aminocyclopyrachlor at 320 g ae ha−1 reduced seed germination by 50 to 88% in the first and second study years, respectively. Aminopyralid reduced seed germination by 94% in the first study year, but only 20% in the second year. When applied to downy brome plants in the early heading stage at approximately 1,235 GDD (LPOST), aminocyclopyrachlor at 320 g ae ha−1 reduced seed germination by 100% both years. Aminopyralid reduced seed germination by 95% in the first year, and 81% in the second year. Other than the observed reduction in seed germination, herbicides did not produce any visible changes in downy brome aboveground plant growth or development. Because downy brome seeds are relatively short-lived in soil, aminocyclopyrachlor and aminopyralid applications to downy brome–infested rangelands and other natural areas could result in reductions in downy brome population densities over time. No published data exist on the effect of aminocyclopyrachlor on seed production of desirable perennial grasses in natural ecosystems, thereby suggesting the need for further research.
Introduced North American Black Henbane (Hyoscyamus niger) Populations are Biennial
Authors: Fettig Christa E. , Hufbauer Ruth A.
Published: December 2014

Black henbane can be either annual or biennial. We investigated which life cycle is found in four introduced western North American populations. Plants were grown in a greenhouse common garden until half were vernalized by exposure to natural winter temperatures, while the other half remained in the greenhouse above 20 C, with 16 h of light and 8 h of dark. In total the plants were monitored 313 d after germination. We measured whether plants bolted, the time it took for bolting to commence, and the size at bolting. All vernalized plants bolted after 117 d of active growth (within 26 d of the end of the vernalization treatment), whereas only 26% of the nonvernalized plants bolted after an average of 278 d of active growth. Vernalized plants bolted at a smaller size than the nonvernalized plants that bolted (28 vs. 41 leaves on average). In the nonvernalized plants, the relationship between time to bolting and size was strong, but not so with the vernalized plants. Our results indicate that introduced black henbane plants are biennial, and that vernalization is more critical to bolting and flowering than reaching a certain size. Nonetheless, the fact that nonvernalized plants were capable of bolting if grown long enough suggests that vernalization is not the only cue that can trigger reproduction in introduced populations.
Models of Invasion and Establishment for African Mustard (Brassica tournefortii)
Authors: Berry Kristin H. , Gowan Timothy A. , Miller David M. , Brooks Matthew L.
Published: December 2014

Introduced exotic plants can drive ecosystem change. We studied invasion and establishment ofBrassica tournefortii(African mustard), a noxious weed, in the Chemehuevi Valley, western Sonoran Desert, California. We used long-term data sets of photographs, transects for biomass of annual plants, and densities of African mustard collected at irregular intervals between 1979 and 2009. We suggest that African mustard may have been present in low numbers along the main route of travel, a highway, in the late 1970s; invaded the valley along a major axial valley ephemeral stream channel and the highway; and by 2009, colonized 22 km into the eastern part of the valley. We developed predictive models for invasibility and establishment of African mustard. Both during the initial invasion and after establishment, significant predictor variables of African mustard densities were surficial geology, proximity to the highway and axial valley ephemeral stream channel, and number of small ephemeral stream channels. The axial valley ephemeral stream channel was the most vulnerable of the variables to invasions. Overall, African mustard rapidly colonized and quickly became established in naturally disturbed areas, such as stream channels, where geological surfaces were young and soils were weakly developed. Older geological surfaces (e.g., desert pavements with soils 140,000 to 300,000 years old) were less vulnerable. Microhabitats also influenced densities of African mustard, with densities higher under shrubs than in the interspaces. As African mustard became established, the proportional biomass of native winter annual plants declined. Early control is important because African mustard can colonize and become well established across a valley in 20 yr.
North-East, North-Central, Mid-Atlantic United States and Southern Canada: Japanese Hedgeparsley (Torilis japonica)—A New Invasive Species in the United States?
Authors: DiTommaso Antonio , Darbyshire Stephen J. , Marschner Caroline A. , Averill Kristine M.
Published: December 2014

Japanese hedgeparsley is an annual (or sometimes biennial) forb introduced from Eurasia and found throughout much of the eastern United States and parts of extreme southern Canada. In North America, Japanese hedgeparsley is commonly found in ruderal habitats, such as roadsides, railroad rights-of-way, forest edges, and urban waste spaces. This species has not yet been listed as a noxious invasive, but its expanding populations have caused concern in several Midwestern states. The primary threat from Japanese hedgeparsley is its vigorous growth habit, which creates dense patches, and its dispersal ability, facilitated by its clinging, burr-like fruits. Some confusion on identification exists within theTorilisgenus, with similar species (particularlyT. arvensis) frequently misidentified in herbaria and the literature. Here, we review aspects of the etymology, taxonomy, biology, distribution, and management of Japanese hedgeparsley with the objective of increasing awareness of the potential threat posed by this species and its closely related congeners.
Multi-criteria optimisation of the Muskingum flood model: a new approach
Authors: Easa Said M.
Published: December 2014

Existing Muskingum hydrological routing models adopt a single criterion in the calibration process. Some models minimise the sum of the squared deviations between estimated and observed outflows (outflow criterion), while others minimise the sum of the squared deviations between the estimated and observed storages (storage criterion). However, models that adopt the outflow (storage) criterion result in a poor fit to the observed storages (outflows). This paper presents a new approach that incorporates both criteria in the calibration process and aids trade-off analysis. The multi-criteria function is expressed as a weighted function of normalised outflow and storage criteria, representing the deviations from ideal outflow and storage values. The routing procedure is based on the author's four-parameter Muskingum model with constant parameters and the fourth-order Runge–Kutta method. The proposed model was applied to three examples. A criterion weight of 0·4–0·6 was found to produce an excellent trade-off between outflow and storage criteria. The results show that the model substantially improves on both criteria compared with single-criterion models. The proposed model, which properly captures the entire flood propagating characteristics in calibration, should be of interest to hydrological engineers and practitioners.
Análise das Políticas de Incentivos Fiscais nos Municípios Brasileiros: o caso da instalação da Grendene no Município de Teixeira de Freitas – BA
Authors: Oliveira Larissa Gabrielle Soares Marinho de , Alves da Cunha Jacqueline Veneroso , Nascimento Silvério Antônio do , Avelino Bruna Camargos
Published: December 2014

Os incentivos fiscais são mecanismos utilizados pelo Estado para atrair novos investimentos para sua região, com o intuito de gerar crescimento econômico. No entanto, não se sabe ao certo se a concessão desses benefícios realmente gera crescimento para as regiões e renda para a população. Nesse contexto, o objetivo deste estudo consiste em identificar eventuais impactos da política de incentivos fiscais adotada pelo município de Teixeira de Freitas no crescimento e na geração de renda para a população. Para isso, foi utilizada a análise documental e métodos estatísticos. Foram analisadas variáveis que são influenciadas pela concessão dos incentivos fiscais, tais como o PIB, admissões e desligamentos no período, comportamento das indústrias, arrecadação e repasse de ICMS e repasse de IPI, bem como o recente levantamento do IBGE sobre o perfil dos municípios brasileiros. De modo geral, os dados apontaram para um crescimento econômico do município, o que tende a corroborar a premissa de cunho teórico de que os incentivos fiscais efetivamente geram crescimento econômico. Porém, não se pode afirmar, somente a partir da realização desta pesquisa, que tal crescimento foi gerado pela concessão de incentivos fiscais. Nesse sentido, o presente estudo contribui para tornar esse assunto mais evidente e fomentar novas pesquisas.
Nível de conformidade do pronunciamento CPC 28: uma análise nas companhias abertas brasileiras
Authors: Silva Josilaini da , Fonseca Larissa de Matos , Nogueira Daniel Ramos
Published: December 2014

A pesquisa teve por objetivo analisar a conformidade das empresas com o CPC28 – Propriedades para Investimentos, para verificar se elas estão divulgando as informações exigidas pelo CPC28. Para atingir o objetivo proposto, foram coletadas e analisadas as demonstrações contábeis e notas explicativas findas em dezembro de 2012. Foram analisadas as informações publicadas pelas empresas baseando-se nos itens de divulgação do CPC28. Os itens foram divididos em blocos, o bloco 1 itens obrigatórios para todas as empresas, o bloco 2 somente para as que optaram mensurar pelo método de custo, e o bloco 3 para empresas de valor justo. Foram analisados de forma descritiva os níveis de divulgação para cada item, realizou-se ainda um teste estatístico, para verificar se quanto maior o saldo das PPI sobre o ativo total maior o nível de divulgação, essa variável obteve correlação média positiva, Foi possível verificar que o nível de divulgação para empresas que optaram pelo método de custo foi mais satisfatório do que aquelas que optaram pelo valor justo. Aquelas que obtiveram maior percentual de divulgação são as empresas do ramo de exploração de imóveis, que possuem em seus balanços valores significativos de Propriedades para Investimento, de onde auferem suas rendas. Outro ponto encontrado é que existe uma dificuldade de evidenciação nas demonstrações e nas notas explicativas, visto que algumas empresas colocam a mesma informação em tópicos diferentes no balanço, além de observar que a maioria das empresas ainda está com nível de divulgação baixa. A pesquisa demonstra que há omissão de itens importantes para a análise dos usuários, dificultando a comparabilidade entre as empresas.
Gestão pública através de mapas estratégicos do Balanced Scorecard: um estudo de caso do Festival Floripa Teatro Isnard Azevedo
Authors: Petri Sérgio Murilo , Rosa Marcelo Medeiros da , Bernardo Fabiano Domingos , Bianco Patrícia
Published: December 2014

A melhoria na gestão é assunto iminente no Serviço Público, remetendo, aos gestores, a busca por novas formas de gerir, com vistas a atingir o objetivo final do Estado - atender às necessidades da população. A adequação das diretrizes estratégicas com os processos organizacionais permite a identificação, compreensão e coordenação dos processos administrativos de maneira eficiente, proporcionando o cumprimento dos princípios constitucionais da Administração Pública. Com o objetivo de contribuir para esta discussão, o presente artigo propõe a utilização do Mapa Estratégico do Balanced Scorecard para melhoria e aperfeiçoamento da gestão estratégica e orçamentária dos entes públicos. Quanto aos aspectos metodológicos, o estudo apresenta caráter científico, exploratório, com abordagem qualitativa e é classificado como um estudo de caso. Os instrumentos de pesquisa foram: a análise documental; a aplicação de questionário com a direção da Fundação Cultural de Florianópolis Franklin Cascaes (FCFFC) e coordenação do Festival Floripa Teatro Isnard Azevedo; e a observação, mediante visitas técnicas à entidade e à 18ª edição do evento, ocorrida em 2011. Ao longo do estudo ficam evidenciadas as vantagens da adaptação do Balanced Scorecard na esfera pública por meio da construção do Mapa Estratégico do festival, permitindo a interação entre as quatro perspectivas - financeira, clientes, processos internos e aprendizado e crescimento e a missão da FCFFC, bem como da percepção do papel da ferramenta como norteador das decisões estratégicas e orçamentárias do evento e da entidade.
Evaluation of upgrading a full-scale activated sludge process integrated with floating biofilm carriers
Authors: Ge Shijian , Zhu Yunpeng , Qiu Shuang , Yang Xiong , Ma Bin , Huang Donghui , Peng Yongzhen
Published: December 2014

This study evaluated the performance of a full-scale upgrade of an existing wastewater treatment plant (WWTP) with the intermittent cyclic extended aeration system (ICEAS), located in Qingdao, China. The ICEAS system was not able to meet effluent standards; therefore, a series of modifications and control strategies were applied as follows: (1) floating plastic carriers were added to the tank to aid biofilm formation; (2) operation parameters such as mixing and aeration time, feeding rate, and settling time were adjusted and controlled with a real-time control system; (3) a sludge return system and submersible water impellers were added; (4) the aeration system was also improved to circulate carriers and prevent clogging. The modified ICEAS system exhibited efficient organic and nutrient removal, with high removal efficiencies of chemical oxygen demand (89.57 ± 4.10%), NH4+-N (95.46 ± 3.80%), and total phosphorus (91.90 ± 4.36%). Moreover, an annual power reduction of 1.04 × 107 kW·h was realized as a result of these modifications.
Evaluation of approaches to quantify total residual oxidants in ballast water management systems employing chlorine for disinfection
Authors: Zimmer-Faust Amity G. , Ambrose Richard F. , Tamburri Mario N.
Published: December 2014

With the maturation and certification of several ballast water management systems that employ chlorine as biocide to prevent the spread of invasive species, there is a clear need for accurate and reliable total residual oxidants (TRO) technology to monitor treatment dose and assure the environmental safety of treated water discharged from ships. In this study, instruments used to measure TRO in wastewater and drinking water applications were evaluated for their performance in scenarios mimicking a ballast water treatment application (e.g., diverse hold times, temperatures, and salinities). Parameters chosen for testing these technologies in the past do not reflect conditions expected during ballast water treatment. Salinity, temperature, and oxidant concentration all influenced the response of amperometric sensors. Oxidation reduction potential (ORP) sensors performed more consistently than amperometric sensors under different conditions but it may be difficult to correlate ORP and TRO measurements for the multitude of biogeochemical conditions found naturally in ballast water. N,N-diethyl-p-phenylenediamine (DPD) analyzers and amperometric sensors were also tested under intermittent sampling conditions mimicking a ballasting scenario, with cyclical dosage and discharge operations. When sampling was intermittent, amperometric sensors required excessive response and conditioning times, whereas DPD analyzers provided reasonable estimates of TRO under the ballasting scenario.
Preliminary evaluation of ecological risk for the city area from the Pearl River Estuary
Authors: Chen Qiuying , Ho KinChung , Liu Jingling
Published: December 2014

It is essential to evaluate the ecological risk for the estuary cities area for the environmental restoration of the estuary. The ecological risk of six city areas from the Pearl River Estuary were evaluated by using the relative risk model. The relative risk assessment method was developed by considering the river network density in the sub-region. The results indicated that Dongguan had the largest ecological risk pressure with total risk scores as high as 10,846.3, and Hong Kong had the lowest ecological risk pressure with total risk scores up to 4,104.6. The greatest source was domestic sewage with total risk scores as high as 1,798.6, followed by urbanization and industry. Oxygen-consuming organic pollutants, organic toxic pollutants and nutrients were the major stressors of the water environment. In terms of habitats, the water environment was enduring the greatest pressure. For the endpoints, water deterioration faced the largest risk pressure.