The Moral Dilemmas of Fighting Terrorism and Guerrilla Groups discusses the most important ethical dilemmas associated with the fight against terrorist organizations and guerilla groups by providing ...readers with a rigorous, yet accessible analysis of how these forms of violence can be justified and how they ought to be fought by entities targeted by groups resorting to these strategies. It will be valuable to anyone interested in understanding the main ethical questions associated with these forms of political violence and the way they can be addressed. After providing conceptual clarifications that will allow the reader to distinguish between terrorism and guerrilla warfare, it explains and discusses what the criteria are that can justify resorting to lethal violence on the part of the latter group as well as the criteria that can determine the identity of those who can legitimately be targeted by these groups. The book analyzes when terrorists ought to be targeted and how this can be done, focusing on the inherent problems associated with the solutions that are normally used against state actors in order to prevent attacks on their part, namely what can be coined as non-violent alternatives to war , such as economic or diplomatic sanctions, arm embargoes and non-violent resistance and, on the other hand, preemptive attacks.
Military Ethics and the Changing Nature of Warfare discusses whether or not the ethical rules of warfare are keeping pace with the changing nature of human conflicts.
Initialization of condensate water variables for convective‐scale weather forecasting has been a topic of active research for the last few years. In this article, we present the addition of ...hydrometeor fields as control variables of a three‐dimensional ensemble variational scheme (3DEnVar) for the cloud‐resolving model AROME‐France. Even without any direct assimilation of hydrometeor observations, analysis increments of hydrometeors can be produced via covariances with observed variables in the ensemble‐derived background‐error covariance matrix. Cycled forecast–analysis experiments in near‐operational conditions have been performed over a three‐month summer period. Three configurations are compared: (i) a control experiment without hydrometeor control variables, (ii) a test experiment with hydrometeor control variables but without cycling the resulting forecasts, and (iii) an experiment with hydrometeor variables and cycled forecasts. Compared with the control experiment, both hydrometeor experiments show a positive impact up to 9 hr of forecasts in terms of cloud cover, and in the first hour for precipitation. The spin‐up period, as evidenced by a reduction of precipitation forecast skill at the beginning of the forecasts, is reduced in length and intensity in the hydrometeor experiments.
Hydrometeor initialization helps greatly in reducing the spin‐up period usually observed after each assimilation step. This positive impact on spin‐up time is evidenced on this graph by the improvements of precipitation scores at the very beginning of the forecast.
Structures that are 3D printed by an extrusion process have periodic geometrical heterogeneity whose influence on the final stiffness properties is not extensively discussed in the existing ...literature. The objective of this article is to quantify the effect of local lace geometry on the anisotropy of extrusion-based 3d printed structures. A numerical homogenisation scheme is implemented to compute an equivalent homogeneous Kirchhoff–Love plate stiffness. The methodology is applied to the parametric study of an oblong lace resulting from oriented-lace pressing. The study reveals that the bending stiffness in the two principal directions may vary by an order of magnitude for common lace geometries, even in the assumption of a perfect bound between layers.
Numerical benchmarks against 3D Finite Element Analysis show that the proposed approach is accurate while significantly decreasing the number of degrees of freedom of the numerical model. Beyond understanding of geometrical defects on the overall stiffness of 3D printed structures, this approach can thus be applied for efficient structural analysis of 3D printed pieces with thousands of layers.
•Periodic geometrical heterogeneity arises from extrusion-based 3d printing.•Equivalent Love–Kirchhoff plate is constructed with periodic homogenisation.•The model is benchmarked with volumetric FEA and previous experiments.•Influence of geometrical heterogeneity cannot be neglected in practice.•Our approach leads to hundred-fold speed-up compared to volumetric FEA.
•A shell-and-tube paraffin/copper foam latent storage unit is studied.•The test rig enables visualization of the melting/solidification front.•The best injection side is determined among top/bottom ...and vertical/horizontal.•An experimental method to estimate charge/discharge times is proposed.•A tube surrounded by copper foam is compared to classical heat exchangers.
Thermal energy storage is an attractive option for effectiveness in many applications such as concentrated solar thermal power or district heating network, since it gives flexibility and reduces energy consumption and costs. The objectives of the present study are to assess copper foam interest as thermal conductivity enhancement technique for latent heat thermal energy storage and to compare copper foam with other heat transfer enhancement systems for shell-and-tubes heat exchangers. The best heat transfer fluid injection side is sought for charge and discharge. Besides, a method is proposed to estimate the characteristic time for melting/solidification and enable comparison between various tests conditions and heat exchanger geometries.
In this paper, a copper foam is implemented in a shell-and-tube heat exchanger as phase change thermal energy storage unit and studied experimentally. Visualization enables the melting/solidification front to be seen, followed and recorded. Bottom and top injection for charge and discharge are compared, vertically and horizontally. It appears that vertical charge and discharge are faster than horizontal ones and that top charge and discharge are faster than bottom ones, thus assessing the significance of volume expansion and natural convection for heat transfer in the phase change material. Moreover, the tested copper foam enhanced geometry is compared with other heat exchangers such as finned copper tube, tube surrounded by carbon foam and a simple tube. It is shown that copper foam combines low-density with high heat transfer performance since it is as efficient as copper fins with half the copper mass, and far more efficient than other presented heat exchangers. Besides, a method for estimating solidification and melting time is proposed. Based on a thermocouple network, this method rests upon measured temperatures inside the phase change material.
•using a programmable 6-axis industrial robot arm to perform measurements with improved positioning accuracy and automatization.•Achieving full-field velocity measurements with an affordable ...setup.•implementation of an open-source software dedicated to the proposed setup.•using a virtual twin of the experiment aiming to the design, the simulation and the control of the experiment.•comparison of the measurement data with numerical results.
An original experimental setup, dedicated to the measurement of the dynamic response of structures, is presented. Called the Robotized Laser Doppler Vibrometer (RLDV), it consists in the assembly of a fixed point Laser Doppler Vibrometer (LDV) on a 6-axis industrial robot arm. This allows to measure the 3D velocity on the surface of objects with a wide range of shapes and sizes. In comparison with commercially available solutions, it represents an affordable and versatile tool. First, the motivations and the new challenges associated to the use of a robot arm to do such experiments are discussed. Second, the different strategies implemented to overcome these difficulties are developed. A software solution is proposed. By the use of a virtual model of the experimental setup, the measurement procedure can be designed and simulated in order to preview robot motion and avoid collisions. With a small number of parameters, the good proceeding of the measurement can be insured on a fine measurement mesh. The software is completed by an interface that allows for the setting of the signal acquisition parameters. At the end, all the procedure is automated and long measurements can be achieved with a reduced supervision. To illustrate the proposed setup, an experimental application is developed. The 3D modal shapes of a curved beam are measured and compared with numerical predictions, showing an excellent correlation.
This paper introduces a novel rheological technique allowing for the assessment of printable materials yield stress at nozzle exit in the case of extrusion-based 3D printing. This technique is ...derived from the analysis of the specific gravity-induced non-Newtonian flow that takes place at nozzle exit, which is at the origin of the formation of material drops or so-called slugs. A simple connected balance located below the nozzle gives access to the slugs mass distribution, the average value and the variability of which allow for the computation of the yield stress and, in parallel, for the assessment of the material homogeneity. In this paper, this method is first experimentally validated on simple materials in simple extruders before it is applied to a real printing system. The equations allowing for the yield stress computation are derived. The accuracy of the technique and its range of applicability are discussed.
The control of mortar rheology is of paramount importance in 3D printing concrete by extrusion. This is particularly sensitive for two-component (2K) processes that use an accelerator to switch the ...printed mortar very quickly from a liquid behavior to a sufficiently solid behavior to be able to be printed (i.e. structuration). After some main key points about measuring the structuration of printed mortars, we propose an original and simple inline test using a pocket shear vane tester. The test is able to measure over several decades of yield stress range, mobilizes small quantities of mortar and enables in-situ measurements on freshly printed layers. The results highlight the difference of structuration between a benchtop-prepared printable material and a truly printed material, fostering the importance of inline measurements, and demonstrating the quality of the method. This pocket shear vane test appears as good contender for a light and affordable rheometer for 2K printable mortars.
•A 3DCP inline pocket vane test that suits fast structuration (100 Pa/s) is proposed.•A linear model fits early structuration of mortars accelerated by aluminum sulfate.•Potential of 2K strategies in adjusting structuration on the fly is demonstrated.•Inline and laboratory measurements differ : Inline testing is a necessity.•A methodology to choose and qualify 3DCP structuration tests is proposed.
Important developments in additive manufacturing with concrete have been achieved in the past decades. Yet, printed components usually do not comply with building standards or basic reliability ...principles, and are not commonly used as load-bearing components. A gap between research and practice exists and despite several attempts, off-the-shelf commercial solutions for the reinforcement of the 3D printed structural components seem always expected. This article presents an alternative (pending for patent 1) for reinforcement of 3D printed structures. This technology inspired by the composite industry is called Flow-Based Pultrusion for additive manufacturing (FBP). A strict control of the rheological behavior of the cementitious matrix ensures the routing and impregnation of continuous rovings of thin fibres (glass, basalt, etc.) without any motorization. The resulting material, Anisotropic Concrete, homogeneously reinforced in a single direction, provides new possibilities, may enhance strength and ductility for hardened material but also help to a better handling of the fresh laces during the deposition, permitting inclined or cantilever paths. This paper describes the process, its constraints, first experimental achievements and first investigations about the mechanical performances of such a material.
•Flow-based reinforcement of 3D printed structures with continuous fibres.•Anisotropic Concrete for new optimised constructive solutions.•No motorization needed for fiber deposition.•Easier handling of the reinforced fresh lace, avoiding slug and buckling.•Reinforcement of the hardened material, improvement of strength and ductility.
The paper presents new results about the geometry of topological interlocking masonries and some possibilities they present to build without formwork. Construction without the use of formwork may be ...an important issue concerning both productivity increase and decreasing of waste generated on a construction site. Due to the development of computational design and robotics in the construction industry, it makes sense to (re)explore innovative design and process of complex masonry structures. The design of this kind of masonry is standard for planar structures, and in this paper, a generalisation is proposed for the parametric design of curved structures. To achieve this, a criterion for translationally interlocked structure based on quadrilateral meshes is exhibited. The application of this criterion is then extended to masonry structures derived from other patterns. Physical prototypes of topological interlocking masonry are also presented. One of these designs seems to allow construction without formwork.
•The context of the work concerns the development of robotics in construction.•The focus is set on complex masonry structures, and topological interlocking systems.•A new design criterion, for translational interlocked free-form structures is proposed.•This criterion is used to design masonry structures constructible without formwork.•Experimental prototype results are discussed.
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