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Highlights • Mass fraction difference as the driving force for the mass transfer. • New variable to fit experimental data for absorption chillers. • Linear relation of cooling capacity to mass fraction difference. • Less deviation compared to characteristic temperature function. Abstract Absorption chillers are considered as heat transfer devices and hence most commonly modeled as heat transfer processes. The absorption of the refrigerant vapor though inherently involves mass transfer into the absorbent, which in comparison to the heat transfer usually is a slow transport process. Modeling absorption chillers, however, usually does not include this mass transfer process. This in fact neglects the dominant process in absorption chillers which is addressed in the present paper. [ABSTRACT FROM AUTHOR]

In this article we present a model describing a laminar film flow over a vertical isothermal plate whilst heat and mass transfer is occurring. We focus on a formulation where most common assumptions, such as constant property data and constant film thickness, have been cancelled. The hydrodynamic model results in longitudinal and transversal velocity components and their evolution in the entrance region. Heat and mass transfer occurs simultaneously and is modelled with respect to release of differential heat of solution as well as heat flow due to interdiffusion. The numerical solution is obtained by utilising a Newton-Raphson method to solve the finite difference formulation of the governing equations. Mass transfer across the film affects the development of both longitudinal and transversal velocity components. The hydrodynamics are modelled using a boundary layer approximation of the Navier-Stokes equations. The significance of simplifications on the hydrodynamic model are illustrated and discussed using a fully developed velocity profile (Nusselt flow) and a plug flow at the inlet for comparison. Even if a Nusselt profile is assumed, it develops further since mass is absorbed or desorbed. It is found that the onset of absorption occurs at shorter flow length when applying a plug flow at the inlet. If the film is initially in equilibrium, this results in a 9.3% increase in absorbed mass over a length of 0.03 m as compared with the Nusselt flow. A fluid with a viscosity five times the one of lithium bromide solution but sharing comparable properties apart from that, leads to lower overall heat and mass transfer rates. If the respective fluids are saturated at the inlet, the accumulated mass flux absorbed by lithium bromide solution is 2.2 times higher than the one absorbed by a high viscous fluid. However, when a plug flow is applied and the fluid is sub-cooled, ab initio the absorbed mass flux is slightly higher for a high viscous fluid. Assuming a sub-cooling of 3 K at the inlet, lithium bromide solution now only performs around 11% better as compared with a high viscous fluid over the considered length of 0.03 m. The code may be downloaded from: https://github.com/mittermaier/hmt. [ABSTRACT FROM AUTHOR]

The present paper analyzes the feasibility of an exhaust gas driven jet-ejector cooling system for charge air cooling of turbocharged gasoline engines in addition to the conventional charge air cooler to increase the engine efficiency. Thereto, steady-state experiments of a jet-ejector cooling system and an exhaust gas heat exchanger prototype working with the refrigerant R134a are used to analyze the operation and control of the compound system and determine feasible cooling capacities, charge air temperatures, thermal COP th and hydraulic COP h . Moreover, the cooling system is rated regarding its power densities and engine backpressure. The exhaust gas waste heat recovery, system power densities, and engine backpressure are acceptable. However, the hydraulic COP h and the amount of reject heat need to be improved, necessitating for instance a multi-staging of the jet-ejection. [ABSTRACT FROM AUTHOR]

A comparison of absorption and desorption is conducted using a detailed model describing heat and mass transfer. First, the influences of various assumptions have been evaluated. Second, typical conditions for both absorption chillers and heat transformers have been defined. The performance of absorption and desorption processes have been analysed for a flow length of 0.1 m. In an absorption chiller, during desorption, the viscosity is lowered and the mass diffusivity is increased. These circumstances cause a 46% higher transfer rate as compared to absorption. Thus, the overall performance of the process is determined by the absorber component. In a heat transformer, during absorption at an elevated pressure and temperature level, the viscosity is lower and mass diffusivity is higher as compared to desorption. Therefore, the transfer rate of during absorption is 10% higher as compared to desorption. Hence, the desorber performance is somewhat more influential to the overall system performance. [ABSTRACT FROM AUTHOR]

Due to their simplicity, jet-ejector cooling systems have been investigated for different applications despite their lower thermal COP th in comparison to alternative thermally-driven cooling technologies. The present paper aims at the derivation of a simple method of representation of the operation characteristics of a jet-ejector cooling system for changing boundary conditions. Thereto, a jet-ejector cooling system operating with the refrigerant R134a has been experimentally investigated in double choking operation of the jet-ejector. The jet-ejector operation is characterized by the entrainment ratio μ in dependence of the adequate stagnation pressure ratios. The results are discussed in a non-dimensional graph as a three dimensional surface from which characteristic lines may be deduced. In several graphs, the motive, condenser and evaporator pressures are linked with the entrainment ratio μ , the cooling capacity Q ˙ 0 , the thermal COP th and the hydraulic COP h allowing a comprehensive determination of the system operation. [ABSTRACT FROM AUTHOR]

The geometrical simplicity of a jet-ejector is in stark contrast to the complexity of the flow phenomena occurring in ejector operation. The available flow models range from empirical models to models based on computational fluid dynamics, differing considerably in complexity and thus explanatory power. The one-dimensional flow models of semi-empirical nature are based on experiments at comparatively low motive pressures and thus on ideal gas equations. In contrast, a one-dimensional, experimentally validated model of a jet-ejector in critical double choking operation which includes real gas effects and relies on a single physically interpretable loss coefficient is introduced in the present paper. Real gas effects impact on the state quantities and the critical mass flow of the expansion in the supersonic nozzle in particular which should be considered in the determination of the entrainment ratio or the absolute motive and suction mass flows of the ejector and in ejector design. [ABSTRACT FROM AUTHOR]

Abstract: Since the late seventies of the 20th century, several analytical models for combined heat and mass transfer in laminar falling film absorption have been proposed. Nevertheless the analytical solutions obtained with the Fourier method for the coupled process are complex and for short flow length a certain instability occurs which have been explained with the inconsistency of the initial and boundary conditions. Therefore boundary layer models have been justified in order to solve the transfer problem for short flow length. Moreover a linear approximation of the phase equilibrium is required. The analytical solutions for heat and mass transfer presented in this paper are obtained by using the Laplace transform to solve the partial differential equations for an isothermal as well as impermeable wall. An originally unknown constant temperature and mass fraction boundary condition at the interface are set. The temperature and mass fraction profile across the film are obtained formally independently. In order to determine the yet unknown interface temperature and mass fraction the phase equilibrium and the interface energy balance are applied, using averaged gradients with regard to the streamwise coordinate. The interface temperature and mass fraction obtained with this procedure are interpreted and treated as mean values. From the known evolution of the mean interface temperature and mass fraction, the local values are derived by inverting the first mean value theorem for integration. The results show very good agreement to the established analytical solutions. The solving procedure does not depend on the input parameters such as the Lewis number for instance, which is needed in order to determine the eigenvalues within the Fourier method. Moreover arbitrary correlations for the phase equilibrium are applicable. The present solution is mathematically stable and offer explicit expressions in order to calculate the mean heat and mass fluxes directly. Therefore this solution is favourable to implement entire absorption process simulation, yet describing the coupled heat and mass transfer process comprehensively. [Copyright &y& Elsevier]

Abstract: For the control of experimental sequences composed of triggers, gates and delays a Pulse-Pattern Generator (PPG) has been developed based on a Field Programmable Gate Array (FPGA) addressed in a LabVIEW environment. It allows a highly reproducible timing of measurement procedures by up to 64 individual channels with pulse and delay periods from the nanoseconds to the minutes range. The PPG has been implemented in the context of the development of a new control system for the ClusterTrap setup, an ion storage device for atomic-cluster research, in close contact with the SHIPTRAP and ISOLTRAP collaborations at GSI and CERN, respectively. As the new PPG is not ion-trap specific it can be employed in any experiment based on sequences of triggers, pulses and delays. [Copyright &y& Elsevier]

Results from the measurement of the heat of reaction of hydrothermal carbonization by power compensated differential scanning calorimetry exhibited a comparably high experimental standard deviation of around 10-20%. The reasons for this standard deviation have been investigated and are being presented in this article. The zeroline deviation and its repeatability showed a decisive influence on the measurements due to the length of the thermal effects (several hours) and the experimental setup (high thermal capacity due to pressure capsules and hydrothermal conditions, type of calorimeter). It was quantified by reference runs and compensated mathematically. In addition, conceptual issues due to the propagation of uncertainty by sum operations are derived. There is an optimum peak length after which the uncertainty rises due to this uncertainty propagation. This optimum is at a signal level within the noise level. However, the contribution of this uncertainty showed little significance compared to the zeroline deviation and thus could be neglected. Results from hydrothermal carbonization of glucose show a mean value of 1060 J/g with a standard deviation of 14% for the presented experimental setup. These values include compensations of systematic errors, including the zeroline deviation, baseline correction, leakage, and transient effects, which are discussed in detail. [ABSTRACT FROM AUTHOR]

Abstract: The use of storages for sensible heat is limited because parts of the input thermal energy end up as unavoidable heat losses. In order to minimize this loss, it is necessary to keep the surface area to volume ratio (S/V) as low as possible. This occurs when the volume of a body with a certain shape increases. In addition to a large volume it is important to use materials with a high volumetric thermal capacity, as long as sensible heat is being used for storage. This condition is best met by water or a combination of substances with water. In the field of interseasonal storages, for solar heat to cover the heating demands of small residential buildings, the general belief is that the relative small volume needed, results in too much heat loss and therefore individual seasonal storages seem to be of no useful solution. However, the theoretical considerations and simulations in this paper show that this is a prejudice. It is possible to supply a great deal of the thermal energy needed for small residential homes with interseasonal ground storage for solar heat. The loss of heat is acceptable if the storage is designed in the correct way. The ground heat storage should be of cuboidal shape, using the local soil as storage material, if possible. The storage containment must be heat-insulated and damp-proof. The placement of the storage could be within the heated building, adjacent to it or nearby. As such systems may be useful as retrofit for existing houses this study assumes that the storage system has no contact with the heated house. The heat is supplied by evacuated tube solar collectors and their feature to produce effective heat with high temperature (above 100°C) is used. [Copyright &y& Elsevier]

Abstract: The Stefan-number is one out of the multitude of dimensionless numbers which predominantly are used in chemical engineering or heat and mass transfer problems. It relates sensible heat to latent heat and is a key number in solving the problem of heat transfer during solidification or melting. However, numbers similar to this show up also when several thermodynamic problems or relationships in refrigeration engineering are analyzed. Using the Stefan-number it can be distinguished if a refrigerant superheats or condenses during compression, it gives the size of the throttling loss, and it helps to decide if a suction line heat exchanger is beneficial or not. For absorption heat pumping, it allows to quantify the most important loss mechanism, the solution heat exchanger loss. Of course, all this information can be acquired in different ways – and maybe in more precise ways – also, but at least for teaching the basics of refrigeration the Stefan-number is simple to use and very easy to understand. In this paper, the different ways of how to use the Stefan-number in teaching and understanding thermodynamics of refrigerants are presented. [Copyright &y& Elsevier]

Abstract: Heat pumping devices which are operating on sorption effects comprise at least two times two categories, namely liquid or solid sorption cycles on the one hand, and open or closed cycles on the other hand. For the benefit of energy saving and the environment as well as for the further development of the technology it is important to be able to compare and evaluate these options in the context of the respective application. Some ideas to this end are shown in this paper. First the meaning of temperatures and humidity for the difference between open and closed systems is discussed, and there are a lot of similarities. Then some differences between solid and liquid sorption which are especially important for the question of minimum operating temperature and part load behavior are being reviewed, and we find that there is something to learn, mutually. Finally the consequences of solar fraction, auxiliary power consumption, and cogeneration efficiency are being highlighted, in order to check the perception of sorption systems to be environmentally benign. These consequences are important for all kinds of sorption cooling systems. It can be expected that there are significant improvements in the efficiency of power plants and compression cooling systems; consequently we find that sorption technology must improve its performance considerably also in order to stay competitive. [Copyright &y& Elsevier]

The relevant low-frequency modes of plan-asymmetric tall buildings and those of bridges consist of coupled translational and torsional motions. We consider the locations of the modal centers of velocity of either the rigidly assumed floors or of the bridge cross-sections to be crucial for selecting the design and the “optimal” position of the liquid absorbers. Such a tuned liquid column-gas damper, TLCGD consists of a sealed rigid piping system that is partially filled with liquid (preferably water), whose dynamics can be derived using the nonstationary Bernoulli equation properly extended to account for the relative streamline in a moving reference system. Although both the construction and working principle of TLCGDs differ from tuned mass dampers (TMD), a geometric analogy exists between these absorber types. Consequently, in a first step modal tuning is performed by means of a transformation of the TMD optimal parameters, e.g., of the Den Hartog formulas, possibly followed in a second step by fine-tuning in state-space. Such a U- or V-shaped sealed liquid column-gas damper, i.e., with the gas-spring effect taken into account, is found suitable for applications in moderately plan-asymmetric buildings (the floors’ modal center of velocity falls outside of the floor plan) and for bridges with dominant horizontal vibrations. The novel design of a torsional sealed liquid column-gas damper, TTLCGD, turns out to have even higher efficiency in effectively damping strongly asymmetric buildings, where the floors’ modal centers of velocity lie inside of the floor plan: in that case of an alternative design, the mid-plane of the U-shaped TLCGD is bent to a cylindrical surface that might be “nearly closed” such that the trace in the floor becomes approximately a loop. For bridges with dominating vertical flexural vibrations, a novel pipe-in-pipe design of the VTLCGD provides the vertical control force rendering the additional efficient damping. The evident features of TLCGDs are no moving mechanical parts, cheap and easy implementation into civil engineering structures, simple modification of the natural frequency and even of the damping properties, low maintenance costs, little additional weight in those cases where a water reservoir is required, e.g., for the sake of fire fighting, and with a performance comparable to that of TMDs of the spring-mass- (or pendulum-)-dashpot type. [ABSTRACT FROM AUTHOR]

Abstract: This paper is the first of two which presents the development of a dynamic model for single-effect LiBr/water absorption chillers. The model is based on external and internal steady-state enthalpy balances for each main component. Dynamic behaviour is implemented via mass storage terms in the absorber and generator, thermal heat storage terms in all vessels and a delay time in the solution cycle. A special feature is that the thermal capacity is partly connected to external and partly to internal process temperatures. In this paper, the model is presented in detail. For verification, the model has been compared to experimental data. The dynamic agreement between experiment and simulation is very good with dynamic deviations around 10s. General functionality of the model and a more detailed comparison with experimental data are presented in Part II of this paper. [Copyright &y& Elsevier]

Abstract: This paper is the second paper out of two which present the development of a dynamic model for single-effect LiBr/water absorption chillers. The first part describes the model in detail with respect to the heat and mass balances as well as the dynamic terms. This second part presents a more detailed investigation of the model performance, including performance analysis, sensitivity checks and a comparison to experimental data. General model functionality is demonstrated. A sensitivity analysis gives results which agree very well to fundamental expectations: it shows that an increase in both external and internal thermal mass results in a slower response to the step change but also in smaller heat flow oscillations during the transient period. Also, the thermal mass has been found to influence the heat flow transients more significantly if allocated internally. The time shift in the solution cycle has been found to influence both the time to reach steady-state and the transients and oscillations of the heat flow. A smaller time shift leads to significantly faster response. A comparison with experimental data shows that the dynamic agreement between experiment and simulation is very good with dynamic temperature deviations between 10 and 25s. The total time to achieve a new steady-state in hot water temperature after a 10K input temperature step amounts to approximately 15min. Compared to this, the present dynamic deviations are in the magnitude of approximately 1–3%. [Copyright &y& Elsevier]

Abstract: An important drawback of solid sorption systems which are operated in batch mode against liquid sorption systems is the imperfect heat exchange between loaded and unloaded adsorbent, as compared to the almost perfect counter-flow solution heat exchanger. We will discuss a simple hardware solution for a significant improvement. We divide the batch reactors into several compartments, not with respect to the refrigerant side, but with respect to the heat transfer medium (heat exchanger loop). If these compartments have individual and arbitrary heat exchange possibilities with each other the efficiency of heat recovery can be improved from a co-flow characteristic to a cross-flow characteristic. We want to stress that this is different from a multi-bed or multistage arrangement. The method is explained, and an algorithm for deriving the exchange efficiency is given. Although this paper is only meant for outlining the basic mechanism, a proposition for realisation of the external hydronic circuit is given in addition. [Copyright &y& Elsevier]

The proposed numerical analysis of moderately thick plates subject to rather general boundary conditions is based on the direct boundary element method (BEM) in the frequency domain. First order shear-deformation theory of the Reissner–Mindlin-type is considered. A step forward in efficiency is obtained when the force and double force with moment Green''s functions of the rectangular simply supported base plate of the same stiffness are applied. The time-reduced equations of hard-hinged polygonal plates correspond to those of a background Kirchhoff plate having frequency-dependent effective parameters like mass, lateral and in-plane load, and is further forced by imposed fictitious curvatures. This analogy holds even for the quasi-static shear forces and bending moments, i.e., when inertia effects become negligible. Furthermore, it can be shown that, in the static case, these stress resultants for certain groups of Reissner-type shear-deformable plates are identical with those resulting from the Kirchhoff theory in the background. Since this analogy is restricted to hard-hinged supports of straight edges, it is necessary to apply, e.g., the direct BEM of analysis to the plate of general planform and boundary conditions. The main effort is thus to study the properties and effective representations of the Green''s dyadics and their singularities, in view of their proper integration. Similarly as for Kirchhoff plates, the strong singularity of the infinite domain is identified for the rectangular plate and subject to indirect integration. The resulting direct BEM proves to be efficient, robust and, in connection with proper pre- and post-processors, becomes an effective tool of engineering analyses just within the frequency limits given by the first two of the three spectral branches. [Copyright &y& Elsevier]

The article presents a study on the superposition of elastic-plastic waves. It explains various mathematical equations in which Hooke's law is substituting into the Cauchy-Euler equation of motion and states that even plastic shock fronts are rendered by the superposition of all elastic waves. It concludes that the plastic strain includes portions from ductile damage and thermal strain from adiabatic depositing heat in the plastic zone.

The diffraction of a plane solitary wave by a rigid vertical circular cylinder and the resulting wave loading on the cylindrical surface are investigated. Based on the higher-order Boussinesq equations, the second order approximation for the solitary wave equation is derived. The analytical solution is obtained by means of a Fourier transformation technique. Investigation of the wave action on the vertical cylinder is of importance in harbor — and offshore engineering and, in combination with the wave imaging technique, in the design of “cylindrical” arch-dams with radial extending plane walls. [ABSTRACT FROM AUTHOR]

The article focuses on three-dimensional dynamic for green function which has been expanded in plane waves. It highlights the Helmholtz decomposition model of the displacements which involves in a homogeneous and isotropic solid and yields the set of wave equations. It also investigates the Lapface-transformation in time, oblique instant force, and horizontal instant single forces with equations and numerical analysis.

This study presents an experimental investigation of the heat transfer occurring during reflux condensation of refrigerant R134a in an inclined micro-fin tube (0.008 m OD, 0.5 m length). The experiments were carried out at a system pressure of 0.74 MPa and at inclination angles of 30°, 38°, 45°, 60° and 90° from the horizontal. The experiments indicated that the inclination angle has a significant effect on heat transfer during reflux condensation. The maximum reflux heat transfer coefficient was found at 30° inclination angle. At this arrangement, the heat transfer increased by a factor of 2.45 compared to the vertical case. A comparison with previous studies suggests that the heat transfer in a micro-fin tube is 2.2 times better than that in a plain tube, and 1.34 times better than that in a plain rectangular channel both at 30° inclination. [ABSTRACT FROM AUTHOR]

Abstract: We present a model describing simultaneous heat and mass transfer of an absorbing or desorbing laminar liquid film flowing over a vertical isothermal plate. We start with a formulation which is comparable to established models by using simplifying assumptions such as homogeneous velocity and constant film thickness. In contrast to those, we allow for effects like change in properties and differential heat of solution within the bulk of the film. Additionally, enthalpy transport due to interdiffusion is accounted for. The impact of the considered effects are discussed and compared. The numerical solution is obtained by utilising a Newton–Raphson scheme to solve the finite difference formulation of the governing equations. Since the temperature gradients adjacent to wall and phase boundary are expected to be large, we discretise the equations on an irregular grid. The results of the model agree very well with established analytical models. It is found that the influence of released differential heat of solution within the bulk is relatively small. However, the impact on the temperature distribution is in the same order of magnitude as the one of a change in properties. Moreover, when comparing desorption with absorption under equivalent conditions, the mass transfer rate during absorption is higher than during desorption. [Copyright &y& Elsevier]

In this paper the dynamic response of compound bridges under moving loads is analyzed. The main structure is modeled as a two-layer beam consisting of a steel girder connected elastically to the concrete deck. The governing sixth-order partial differential equation of motion of the homogenized beam is extended to include uncertainty in the mechanical property of the interface. The slip modulus is considered to be a random variable, whose probability density function is considered to be zero outside of a given interval, that is, it is a member of a fuzzy set with bounded uncertainty. The analysis of the illustrative problem is based on the interval representation with a triangular membership function of the slip modulus assigned. Membership functions of the random natural frequencies are determined. Both, fuzzy peak deflection and acceleration are derived for a single-span compound bridge subjected to a single moving load as well as to a series of repetitive moving loads traveling with constant speed. [ABSTRACT FROM AUTHOR]

Abstract: Various researchers have developed models of conventional H2O–LiBr absorption machines with the aim of predicting their performance. In this paper, the methodology of characteristic equations developed by is applied. This model is able to represent the capacity of single effect absorption chillers and heat pumps by means of simple algebraic equations. An extended characteristic equation based on a characteristic temperature difference has been obtained, considering the facility features. As a result, it is concluded that for adiabatic absorbers a subcooling temperature must be specified. The effect of evaporator overflow has been characterized. Its influence on cooling capacity has been included in the extended characteristic equation. Taking into account the particular design and operation features, a good agreement between experimental performance data and those obtained through the extended characteristic equation has been achieved at off-design operation. This allows its use for simulation and control purposes. [Copyright &y& Elsevier]

Abstract: Heat transfer during reflux condensation in a narrow tube (0.007m inner diameter, 0.5m length) and a rectangular channel (0.007m hydraulic diameter, 0.5m length) was investigated. The basic mechanism of this process, i.e. removing high boiling point components from a stream of a more volatile fluid or even from inert gases, is still not sufficiently understood. The study presents experimental results with the zeotropic mixture of R134a and R123 at a constant composition of the incoming vapour of 50mol%. The results show that both, gas side heat and mass transfer resistances and the resistances in the liquid film influence the condensation process. Channel inclination is less important in mixture condensation than in pure fluid condensation but not negligible, and increasing vapour mass flow enhances mixture condensation. Contrary to pure fluid results heat transfer in the rectangular channel with the same hydraulic diameter is much smaller than in the tube at the same vapour mass flow rate. [Copyright &y& Elsevier]

We review evidence relating to children's ability to acknowledge false beliefs within a simulation account according to which our focus is set by default to the world as we know it: hence, our current beliefs assume salience over beliefs that do not fall into this category. The model proposes that the ease with which we imaginatively shift from this default depends on the salience of our current belief, relative to the salience of the belief that is being simulated. However, children do use a rule-based approach for mentalizing in some contexts, which has the advantage of protecting them from the salience of their own belief. Rule-based mentalizing judgements might be faster, cognitively easier and less prone to error, relative to simulation-based judgements that are much influenced by salience. We propose that although simulation is primary, rule-based approaches develop as a shortcut; we thus grow from individuals capable of using only simulation into individuals capable of both techniques. [ABSTRACT FROM AUTHOR]

Abstract: Ammonia vapour refining is a common procedure in ammonia–water absorption machines. A solar assisted single effect absorption machine that uses the pair ammonia–water was developed and tested. Its desorber has a built-in adiabatic refining column constituted by a rich solution spray. The refining method proved its feasibility. The spray provided a more or less constant ammonia vapour enrichment of about 1% which is enough for the working temperature ranges of this type of machine. It was also verified that the refining effect of the spray is almost independent of the refrigerant vapour and solution mass flow rates. [Copyright &y& Elsevier]

The general theory of linearized elasticity with eigenstrain is considered with applications to continuous, discrete and discretized structures. It is shown that any eigenstrain can be uniquely decomposed into impotent and nilpotent constituents. The proven theorem on decomposition is based on the concepts of functional analysis, in particular, with respect to Hilbert functional spaces. This unique decomposition allows for the individual and independent control of stress, strain and displacement (e.g. shape control). The associated algorithm avoids the cumbersome solution of boundary-value problems with eigenstrain in connection with these control problems. Decomposition of eigenstrain opens the practically important opportunity to fully separate the control of strain and stress produced by force loading. [ABSTRACT FROM AUTHOR]

The theorem on the unique decomposition of eigenstrain provides the tool to construct prescribed displacements inside and (or) at the surface of a linear elastic body in two novel ways (e.g., in connection with shape control). The first approach applies Maysel’s formula and renders the linear relationship between nodal displacements and impotent eigenstrain in discrete or discretized systems. The second, alternative approach can be applied to continuous systems as well, and allows controlling the shape of the body. Both approaches do not require the solution of the associated boundary value problem with prescribed eigenstrain, thus circumventing the possibly cumbersome (numerical) solution, which can present some difficulties with respect to its convergence. [ABSTRACT FROM AUTHOR]

In earlier work, a novel open absorption cycle was proposed, capable of producing both cooling and dehumidification for air conditioning, utilizing low-grade heat. The system, referred to as DER (Dehumidifier-Evaporator-Regenerator), uses ambient air in conjunction with an absorbent solution; the air is dehumidified and then employed to produce chilled water in an evaporative cooler. Alternatively, a portion of the dehumidified air may be used directly for air conditioning purposes. The system thus has the potential to provide both cooling and dehumidification in variable ratios, as required by the load. Computer simulations and theoretical investigations were carried out to analyze and predict the performance of the system. The objective of the present study has been to construct a laboratory system to test the concept, identify problems and carry out preliminary design optimization. The characteristic performance of individual components, analyzed theoretically in the simulation, was studied experimentally. Measurements have provided much-needed realistic data about heat and mass transfer coefficients. The performance of the system has been studied under varying operating conditions. The paper describes the operation of the experimental system and presents the measured data and the resulting transfer coefficients. [ABSTRACT FROM AUTHOR]

The problem of assigning a prescribed thermal stress distribution in a structural part during its thermoelastic deformation is discussed in the first part. The theorem comprising the necessary and sufficient conditions for producing such a prescribed thermal stress distribution is formulated. An objective function is introduced to solve the simple problem of uniaxial stress states in rods. In general, such a function puts the posed problem into the class of optimization problems of the mechanics of deformable solids. Illustrative examples are explicitly solved. The problem of assigning a prescribed thermal strain distribution in a structural part during its thermoelastic deformation is briefly discussed in the second part. A direct approach for its solution is proposed when keeping the thermal stress field constant. The theoretical fundamentals of the method are based on Maysel's formula of uncoupled thermoelasticity. The numerical examples show the effectiveness and reliability of the proposed algorithm. [ABSTRACT FROM AUTHOR]

The production of aluminum cluster tetra-anions, and thus the first observation of a tetra-anionic metal cluster in the gas-phase, is reported. The aluminum cluster polyanions were generated by use of the “electron-bath technique.” The smallest tetra-anion observed was Al2154-, containing 14% fewer atoms than expected from classical estimates of the tetra-anion appearance size. [ABSTRACT FROM AUTHOR]

Background and purpose Charcot−Marie−Tooth ( CMT) 1C due to mutations in LITAF/ SIMPLE is a rare subtype amongst the autosomal dominant demyelinating forms of CMT. Our objective was to report the clinical and electrophysiological characteristics of 18 CMT1C patients and compare them to 20 patients with PMP22 mutations: 10 CMT1A patients and 10 patients with hereditary neuropathy with liability to pressure palsies ( HNPP). Methods Charcot−Marie−Tooth 1C patients were followed-up in referral centres for neuromuscular diseases or were identified by familial survey. All CMT1A and HNPP patients were recruited at the referral centre for neuromuscular diseases of Pitié-Salpêtrière Hospital. Results Two phenotypes were identified amongst 18 CMT1C patients: the classical CMT form (' CMT-like', 11 cases) and a predominantly sensory form ('sensory form', seven cases). The mean CMT neuropathy score was 4.45 in CMT1C patients. Motor nerve conduction velocities in the upper limbs were significantly more reduced in CMT1A than in CMT1C patients. On the other hand, the motor nerve conduction velocity of the median nerve was significantly lower in CMT1C compared to the HNPP group. Distal motor latency was significantly more prolonged in CMT1A patients compared to the CMT1C and HNPP groups, the latter two groups having similar distal motor latency values. Molecular analysis revealed five new LITAF/ SIMPLE mutations (Ala111Thr, Gly112Ala, Trp116Arg, Pro135Leu, Arg160Cys). Conclusions Our study delineates CMT1C as mostly a mild form of neuropathy, and gives clinical and electrophysiological clues differentiating CMT1C from CMT1A and HNPP. Delineating phenotypes in CMT subtypes is important to orient molecular diagnosis and to help to interpret complex molecular findings. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented concerning the case of a patient from a consanguineous Turkish marriage who was reported to have myopathy with tubular aggregates and gyrate atrophy of the choroid and retina due to hyperornithinaemia.

Abstract: A facility for experimental evaluation of innovative components forming part of a single effect LiBr–H2O adiabatic absorption chiller is described. Plate heat exchangers have been incorporated in the design. Two adiabatic absorber configurations, droplets and liquid sheets, were designed and tested and its performances parameters were experimentally determined. Evaporator limitations have been identified and included in the analysis. Liquid accumulation leads to overflow of refrigerant out of the evaporators. Some general observations, regarding particular operating conditions, are reported. The absorber performance has been characterized in terms of heat and mass transfer through the heat conductance and the effectiveness. The influence of the recirculation ratio is presented for both cases. The liquid sheet configuration has shown better evaluation parameters than droplets configuration. A significant reduction in the absorber size (up to 50%) as compared to using droplets is possible. [Copyright &y& Elsevier]

ClusterTrap has been designed to investigate properties of atomic clusters in the gas phase with particular emphasis on the dependence on the cluster size and charge state. The combination of cluster source, Penning trap and time-of-flight mass spectrometry allows a variety of experimental schemes including collision-induced dissociation, photo-dissociation, further ionization by electron impact, and electron attachment. Due to the storage capability of the trap extended-delay reaction experiments can be performed. Several recent modifications have resulted in an improved setup. In particular, an electrostatic quadrupole deflector allows the coupling of several sources or detectors to the Penning trap. Furthermore, a linear radio-frequency quadrupole trap has been added for accumulation and ion bunching and by switching the potential of a drift tube the kinetic energy of the cluster ions can be adjusted on their way towards or from the Penning trap. Recently, experiments on multiply negatively charged clusters have been resumed. [ABSTRACT FROM AUTHOR]

Earlier experiments [Eur. Phys. J. D 43, 241 (2007)] investigating the production of aluminium cluster dianions have been extended to larger cluster sizes for the purpose of producing higher charge states. Polyanions are produced using the “electron-bath technique" which involves the exposure of monoanionic clusters to a bath of low-energy secondary electrons. In this contribution the production of Aln 3- is investigated as a function of cluster size. Relative trianion yields (number of trianions produced relative to the number of precursor anions) were observed to increase from a few percent up to 55% within ~30 cluster sizes. The observed appearance size (n = 103) is in reasonable agreement with the predictions of classical models. [ABSTRACT FROM AUTHOR]

The performance of an advanced triple-pressure level (TPL) single-stage absorption cycle with refrigerant R125 and various organic absorbents were studied. In the developed TPL cycle, a jet ejector of a special design is added at the absorber inlet. The device serves two major functions: it facilitates pressure recovery and improves the mixing process between the weak solution and the refrigerant vapor coming from the evaporator. These effects enhance the absorption process of the refrigerant vapor into the solution drops. To facilitate the design of a jet ejector for absorption machines, a numerical model of simultaneous heat and mass transfer between the liquid and the gas phases in the ejector was developed.Based on the computerized simulation program, a parametric study of a TPL cycle was carried out. Comparison was made between the performances of the TPL and the common double pressure level (DPL) absorption cycle with refrigerant R125 and various organic absorbents. In addition, the influence of the jet ejector on the performance of the absorption cycle and the size of the unit was studied. [Copyright &y& Elsevier]

The production mechanism of quasimolecular (MO) x-rays in 40 MeV Ni-Ni collisions was investigated in a multi-parameter experiment. Impact parameter dependent MO x-ray production probabilities were determined. The study of the angular distribution of the emitted radiation allowed the determination of impact parameter dependent alignment parameters for this process. Triple coincident MO x-ray - Ni K x-ray - scattered projectile data provided for the determination of state selective MO x-ray production probabilities. The results are compared to dynamical calculations describing the time dependent evolution of the relevant quasimolecular states and the radiative couplings among them. [ABSTRACT FROM AUTHOR]