Method for measuring the lateral aberrations of a lithographic projection system with mirror-symmetric FOCAL marks

A novel method for measuring the imaging quality of a projection system with mirror-symmetric FOCAL marks is proposed, and the principle of the method is described. Through experiments, it is demonstrated that not only the axial aberrations but also the lateral aberrations can be measured with high accuracy by the method. The advantages of the method include obtaining more aberrations than the FOCAL technique and making it much simpler to perform a full-scale measurement of the imaging quality of a lithographic projection system. (C) 2006 Society of Photo-Optical Instrumentation Engineers.

Method for measuring the lateral aberrations of a lithographic projection system with mirror-symmetric FOCAL marks

A novel method for measuring the imaging quality of a projection system with mirror-symmetric FOCAL marks is proposed, and the principle of the method is described. Through experiments, it is demonstrated that not only the axial aberrations but also the lateral aberrations can be measured with high accuracy by the method. The advantages of the method include obtaining more aberrations than the FOCAL technique and making it much simpler to perform a full-scale measurement of the imaging quality of a lithographic projection system. (C) 2006 Society of Photo-Optical Instrumentation Engineers.

A novel method to measure coma aberration of projection system

A novel method to measure coma aberration by pattern displacements at different defocus positions is proposed in this paper. The effect of defocus on coma-induced pattern displacement is analyzed. The measuring principle of the method is described in detail. Using the simulation program PROLITH, the proportionality factors between pattern displacement and coma aberration at different defocus positions are calculated. It is proved that the method is simple to perform and the measurement accuracy of coma can increase approximately by 25% by this novel method. (c) 2006 Elsevier GmbH. All rights reserved.

Double-line-density gratings structure for compression and generation of double femtosecond laser pulses

Grating pairs are widely used for pulse compression and stretching. Normally, the two gratings are identical. We propose a very simple structure with double-line-density reflective gratings for pulse compression and generation of double pulses, which has the advantages of no material dispersion, compact in volume, simple in structure, etc. The use of reflective Dammann gratings fully demonstrated the principle of this structure. The output pulses are well verified by a standard frequency-resolved optical gating apparatus. This structure will be highly interesting in ultrashort pulse compression and other more practical applications of femtosecond laser pulses. (c) 2007 Optical Society of America.

A novel method for measuring the coma of a lithographic projection system by use of mirror-symmetry marks

A novel method for measuring the coma of a lithographic projection system is proposed and the principle of the method is described. By utilizing mirror-symmetry marks, the adverse effects of axial aberrations on the coma measurement are avoided. Experimental results demonstrated that the method has high accuracy. Compared with TAMIS, the conventional technique used for coma measurement, the method is more reliable because the influences of the process factors on the lateral displacements have been considered. (c) 2006 Elsevier Ltd. All rights reserved.

Life history and population dynamics of the finetooth shark (Carcharhinus isodon) in the northeastern Gulf of Mexico

The life history and population dynamics of the finetooth shark (Carcharhinus isodon) in the north-eastern Gulf of Mexico were studied by determining age, growth, size-at-maturity, natural mortality, productivity, and elasticity of vital rates of the population. The von Bertalanffy growth model was estimated as Lt=1559 mm TL (1–e–0.24 (t+2.07)) for females and Lt = 1337 mm TL (1–e–0.41 (t+1.39)) for males. For comparison, the Fabens growth equation was also fitted separately to observed size-at-age data, and the fits to the data were found to be similar. The oldest aged specimens were 8.0 and 8.1 yr, and theoretical longevity estimates were 14.4 and 8.5 yr for females and males, respectively. Median length at maturity was 1187 and 1230 mm TL, equivalent to 3.9 and 4.3 yr for males and females, respectively. Two scenarios, based on the results of the two equations used to describe growth, were considered for population modeling and the results were similar. Annual rates of survivorship estimated through five methods ranged from 0.850/yr to 0.607/yr for scenario 1 and from 0.840/yr to 0.590/yr for scenario 2. Productivities were 0.041/yr for scenario 1 and 0.038/yr for scenario 2 when the population level that produces maximum sustain-able yield is assumed to occur at an instantaneous total mortality rate (Z) equaling 1.5 M, and were 0.071/yr and 0.067/yr, when Z=2 M for scenario 1 and 2, respectively. Mean generation time was 6.96 yr and 6.34 yr for scenarios 1 and 2, respectively. Elasticities calculated through simulation of Leslie matrices averaged 12.6% (12.1% for scenario 2) for fertility, 47.7% (46.2% for scenario 2) for juvenile survival, and 39.7% (41.6% for scenario 2) for adult survival. In all, the finetooth shark exhibits life-history and population characteristics intermediate to those of sharks in the small coastal complex and those from some large coastal species, such as the blacktip shark (Carcharhinus limbatus).

Design and commissioning of a 30kw direct drive wave generator

The Trident Energy TE5 is a prototype wave energy converter operating on the principle of having direct-drive linear generators mounted above the water surface, coupled to floats moving under the rig deck. This paper describes aspects of the TE5 design, including its generators, power electronic systems and the conception of its marine structure.

The double dance of agency: a socio-theoretic account of how machines and humans interact

The nature of the relationship between information technology (IT) and organizations has been a long-standing debate in the Information Systems literature. Does IT shape organizations, or do people in organisations control how IT is used? To formulate the question a little differently: does agency (the capacity to make a difference) lie predominantly with machines (computer systems) or humans (organisational actors)? Many proposals for a middle way between the extremes of technological and social determinism have been put advanced; in recent years researchers oriented towards social theories have focused on structuration theory and (lately) actor network theory. These two theories, however, adopt different and incompatible views of agency. Thus, structuration theory sees agency as exclusively a property of humans, whereas the principle of general symmetry in actor network theory implies that machines may also be agents. Drawing on critiques of both structuration theory and actor network theory, this paper develops a theoretical account of the interaction between human and machine agency: the double dance of agency. The account seeks to contribute to theorisation of the relationship between technology and organisation by recognizing both the different character of human and machine agency, and the emergent properties of their interplay.

The three dimensional structure and biological domains of the p53 C-terminus.

It was expected that there are a coil (289 similar to 325) and two a helix (alpha(1)368 similar to 373, alpha(2)381 similar to 388) structures in p53 protein C-terminal region based on its mRNA secondary structure template and Chou-Fasman's protein secondary structure principle of prediction. The result was conformed by the other four methods of protein secondary structure prediction that are based on the multiple sequence alignment (accuracy = 73.20%). Combine with the 31 amino acids crystal structure of the oligomerization, the three dimensional conformation of p53 C-terminal 108 residues was built using the SGI INDIGO(2) computer. This structure further expounds the relationship among those biological function domains of p53 C- terminus at three-dimensional level.

Magnetically actuated artificial cilia: the effect of fluid inertia.

Natural cilia are hairlike microtubule-based structures that are able to move fluid on the micrometer scale using asymmetric motion. In this article, we follow a biomimetic approach to design artificial cilia lining the inner surfaces of microfluidic channels with the goal of propelling fluid. The artificial cilia consist of polymer films filled with superparamagnetic nanoparticles, which can mimic the motion of natural cilia when subjected to a rotating magnetic field. To obtain the magnetic field and associated magnetization local to the cilia, we solve the Maxwell equations, from which the magnetic body moments and forces can be deduced. To obtain the ciliary motion, we solve the dynamic equations of motion, which are then fully coupled to the Navier-Stokes equations that describe the fluid flow around the cilia, thus taking full account of fluid inertial forces. The dimensionless parameters that govern the deformation behavior of the cilia and the associated fluid flow are arrived at using the principle of virtual work. The physical response of the cilia and the fluid flow for different combinations of elastic, fluid viscous, and inertia forces are identified.

Swimming direction reversal of flagella through ciliary motion of mastigonemes.

Bio-inspired designs can provide an answer to engineering problems such as swimming strategies at the micron or nano-scale. Scientists are now designing artificial micro-swimmers that can mimic flagella-powered swimming of micro-organisms. In an application such as lab-on-a-chip in which micro-object manipulation in small flow geometries could be achieved by micro-swimmers, control of the swimming direction becomes an important aspect for retrieval and control of the micro-swimmer. A bio-inspired approach for swimming direction reversal (a flagellum bearing mastigonemes) can be used to design such a system and is being explored in the present work. We analyze the system using a computational framework in which the equations of solid mechanics and fluid dynamics are solved simultaneously. The fluid dynamics of Stokes flow is represented by a 2D Stokeslets approach while the solid mechanics behavior is realized using Euler-Bernoulli beam elements. The working principle of a flagellum bearing mastigonemes can be broken up into two parts: (1) the contribution of the base flagellum and (2) the contribution of mastigonemes, which act like cilia. These contributions are counteractive, and the net motion (velocity and direction) is a superposition of the two. In the present work, we also perform a dimensional analysis to understand the underlying physics associated with the system parameters such as the height of the mastigonemes, the number of mastigonemes, the flagellar wave length and amplitude, the flagellum length, and mastigonemes rigidity. Our results provide fundamental physical insight on the swimming of a flagellum with mastigonemes, and it provides guidelines for the design of artificial flagellar systems.

Theoretical and experimental analysis of pneumatic balloon microactuators

This paper presents a theoretical and experimental analysis of a biologically inspired balloon-type pneumatic microactuator. The operation principle of pneumatic balloon actuators (PBA's) is based on an asymmetric deflection of two PDMS layers with different thicknesses or different Young's moduli that are bonded together. A new analytical 2D model that describes the complex behavior of these actuators is presented and validated using both 3D FEM models and measurements. The actuators have dimensions ranging from 11 mm × 2 mm × 0.24 mm to 4 mm × 1 mm × 0.12 mm. Their fabrication is based on micromolding of PDMS, and can therefore easily be fabricated in high throughput. Measurements showed that the analytical model provides a qualitative description of the actuator behavior, and showed that the larger actuators are capable of delivering a 7 mm stroke at a supply pressure of 70 kPa and a force of max 22 mN at a supply pressure of 105 kPa. © 2011 Elsevier B.V. All rights reserved.

Development of accurate, robust liquid equations of state for multi-phase CFD simulations with a modified AUSM+-up scheme

Eight equations of state (EOS) have been evaluated for the simulation of compressible liquid water properties, based on empirical correlations, the principle of corresponding states and thermodynamic relations. The IAPWS-IF97 EOS for water was employed as the reference case. These EOSs were coupled to a modified AUSM+-up convective flux solver to determine flow profiles for three test cases of differing flow conditions. The impact of the non-viscous interaction term discretisation scheme, interfacial pressure method and selection of low-Mach number diffusion were also compared. It was shown that a consistent discretisation scheme using the AUSM+-up solver for both the convective flux and the non-viscous interfacial term demonstrated both robustness and accuracy whilst facilitating a computationally cheaper solution than discretisation of the interfacial term independently by a central scheme. The simple empirical correlations gave excellent results in comparison to the reference IAPWS-IF97 EOS and were recommended for developmental work involving water as a cheaper and more accurate EOS than the more commonly used stiffened-gas model. The correlations based on the principles of corresponding-states and the modified Peng-Robinson cubic EOS also demonstrated a high degree of accuracy, which is promising for future work with generic fluids. Further work will encompass extension of the solver to multiple dimensions and to account for other source terms such as surface tension, along with the incorporation of phase changes. © 2013.

Local equilibrium of the Gibbs interface in two-phase systems

We analyze the local equilibrium assumption for interfaces from the perspective of gauge transformations, which are the small displacements of Gibbs' dividing surface. The gauge invariance of thermodynamic properties turns out to be equivalent to conditions for jumps of bulk densities across the interface. This insight strengthens the foundations of the local equilibrium assumption for interfaces and can be used to characterize nonequilibrium interfaces in a compact and consistent way, with a clear focus on gauge-invariant properties. Using the principle of gauge invariance, we show that the validity of Clapeyron equations can be extended to nonequilibrium interfaces, and an additional jump condition for the momentum density is recognized to be of the Clapeyron type. © 2012 Europhysics Letters Association.

Minimalistic models of an energy-efficient vertical-hopping robot

The use of free vibration in elastic structure can lead to energy-efficient robot locomotion, since it significantly reduces the energy expenditure if properly designed and controlled. However, it is not well understood how to harness the dynamics of free vibration for the robot locomotion, because of the complex dynamics originated in discrete events and energy dissipation during locomotion. From this perspective, the goals of this paper are to propose a design strategy of hopping robot based on elastic curved beams and actuated rotating masses and to identify the minimalistic model that can characterize the basic principle of robot locomotion. Since the robot mainly exhibits vertical hopping, three 1-D models are examined that contain different configurations of simple spring-damper-mass components. The real-world and simulation experiments show that one of the models best characterizes the robot hopping, through analyzing the basic kinematics and negative works in actuation. Based on this model, the self-stability of hopping motion under disturbances is investigated, and design and control parameters are analyzed for the energy-efficient hopping. In addition, further analyses show that this robot can achieve the energy-efficient hopping with the variation in payload, and the source of energy dissipation of the robot hopping is investigated. © 1982-2012 IEEE.