Large-scale Experimental Setup Research Articles

Thermal degradation of polyamide 66 and its model compound

Thermal degradation of N, N'-dibutyladipamide and polyamide 66 (PA66) was carried out in a large-scale experimental setup with nitrogen sweeping in order to collect elusive degradation intermediates. At a high nitrogen flow rate, 1-butylazepane-2,7-dione was identified as a major degradation product from the thermal decomposition of N, N'-dibutyladipamide. Upon heating, 1-butylazepane-2,7-dione produced cyclopentanone and its derivatives, dibutylurea and a nitrile that constituted the majority of degradation products of N, N'-dibutyladipamide, proving that the 7-membered heterocycle compound is a crucial primary degradation product as well as a precursor for the secondary degradation products of N, N'-dibutyladipamide. Subsequently, chemistry concerning the generation and decomposition of 1-butylazepane-2,7-dione was developed for the thermal decomposition of DBA. On the other hand, hexamethylenediamine, 1,8-diazacyclotetradecane-2,7-dione, cyclopentanone and its derivatives were collected as important degradation products from the thermal decomposition of PA66. In view of the structural similarity between DBA and PA66 and their comparable degradation products, a mechanism centering on the generation and decomposition of a 7-membered ring has ultimately been established for thermal degradation of PA66.

Reproductive output and other adult life-history traits of black soldier flies grown on different organic waste and by-products

The interest in mass-rearing black soldier fly (Hermetia illucens) larvae for food and feed is rapidly increasing. This is partly sparked by the ability of the larvae to efficiently valorise a wide range of organic waste and by-products. Primarily, research has focused on the larval stage, hence underprioritizing aspects of the adult biology, and knowledge on reproduction-related traits such as egg production is needed. We investigated the impact of different organic waste and by-products as larval diets on various life-history traits of adult black soldier flies in a large-scale experimental setup. We reared larvae on four different diets: spent Brewer’s grain, ground carrots, Gainesville diet, and ground oranges. Traits assessed were development time to pupa and adult life-stages, adult body mass, female lifespan, egg production, and egg hatch. Larval diet significantly impacted development time to pupa and adult, lifespan, body size, and egg production. In general, flies reared on Brewer’s grain developed up to 4.7 d faster, lived up to 2.3 d longer, and produced up to 57% more eggs compared to flies reared on oranges on which they performed worst for these traits. There was no effect of diet type on egg hatch, suggesting that low-nutritious diets, i.e. carrots and oranges, do not reduce the quality but merely the quantity of eggs. Our results demonstrate the importance of larval diet on reproductive output and other adult traits, all important for an efficient valorisation of organic waste and by-products, which is important for a sustainable insect-based food and feed production.

Characteristics of proppant transport and placement within rough hydraulic fractures

A three-dimensional reconstruction of rough fracture surfaces of hydraulically fractured rock outcrops is carried out by casting process, a large-scale experimental setup for visualizing rough fractures is built to perform proppant transport experiments. The typical characteristics of proppant transport and placement in rough fractures and its intrinsic mechanisms are investigated, and the influences of fracture inclination, fracture width and fracturing fluid viscosity on proppant transport and placement in rough fractures are analyzed. The results show that the rough fractures cause variations in the shape of the flow channel and the fluid flow pattern, resulting in the bridging buildup during proppant transport to form unfilled zone, the emergence of multiple complex flow patterns such as channeling, reverse flow and bypassing of sand-carrying fluid, and the influence on the stability of the sand dune. The proppant has a higher placement rate in inclined rough fractures, with a maximum increase of 22.16 percentage points in the experiments compared to vertical fractures, but exhibits poor stability of the sand dune. Reduced fracture width aggravates the bridging of proppant and induces higher pumping pressure. Increasing the viscosity of the fracturing fluid can weaken the proppant bridging phenomenon caused by the rough fractures.

A framework for approximate product search using faceted navigation and user preference ranking

One of the problems that e-commerce users face is that the desired products are sometimes not available and Web shops fail to provide similar products due to their exclusive reliance on Boolean faceted search. User preferences are also often not taken into account. In order to address these problems, we present a novel framework specifically geared towards approximate faceted search within the product catalog of a Web shop. It is based on adaptations to the p-norm extended Boolean model, to account for the domain-specific characteristics of faceted search in an e-commerce environment. These e-commerce specific characteristics are, for example, the use of quantitative properties and the presence of user preferences. Our approach explores the concept of facet similarity functions in order to better match products to queries. In addition, the user preferences are used to assign importance weights to the query terms. Using a large-scale experimental setup based on real-world data, we conclude that the proposed algorithm outperforms the considered benchmark algorithms. Last, we have performed a user-based study in which we found that users who use our approach find more relevant products with less effort.

ORCA-SPY enables killer whale sound source simulation, detection, classification and localization using an integrated deep learning-based segmentation

Acoustic identification of vocalizing individuals opens up new and deeper insights into animal communications, such as individual-/group-specific dialects, turn-taking events, and dialogs. However, establishing an association between an individual animal and its emitted signal is usually non-trivial, especially for animals underwater. Consequently, a collection of marine species-, array-, and position-specific ground truth localization data is extremely challenging, which strongly limits possibilities to evaluate localization methods beforehand or at all. This study presents ORCA-SPY, a fully-automated sound source simulation, classification and localization framework for passive killer whale (Orcinus orca) acoustic monitoring that is embedded into PAMGuard, a widely used bioacoustic software toolkit. ORCA-SPY enables array- and position-specific multichannel audio stream generation to simulate real-world ground truth killer whale localization data and provides a hybrid sound source identification approach integrating ANIMAL-SPOT, a state-of-the-art deep learning-based orca detection network, followed by downstream Time-Difference-Of-Arrival localization. ORCA-SPY was evaluated on simulated multichannel underwater audio streams including various killer whale vocalization events within a large-scale experimental setup benefiting from previous real-world fieldwork experience. Across all 58,320 embedded vocalizing killer whale events, subject to various hydrophone array geometries, call types, distances, and noise conditions responsible for a signal-to-noise ratio varying from -14.2 dB to 3 dB, a detection rate of 94.0 % was achieved with an average localization error of 7.01^circ. ORCA-SPY was field-tested on Lake Stechlin in Brandenburg Germany under laboratory conditions with a focus on localization. During the field test, 3889 localization events were observed with an average error of 29.19^circ and a median error of 17.54^circ. ORCA-SPY was deployed successfully during the DeepAL fieldwork 2022 expedition (DLFW22) in Northern British Columbia, with a mean average error of 20.01^circ and a median error of 11.01^circ across 503 localization events. ORCA-SPY is an open-source and publicly available software framework, which can be adapted to various recording conditions as well as animal species.

User research and design creativity: three insights for future studies

ABSTRACT Understanding users is central to design and Human-Computer Interaction, both for researchers and for practitioners, who often conduct user research and communicate its value to stakeholders and clients. Despite its praised relevance, we know little about how user research affects design creativity. Our objective is to establish a foundation for answering this question. We first review empirical findings from related domains and examine how the value of user research is linked to design creativity. We then present a pilot study for a large-scale experimental setup to determine how different levels of user research influence design creativity. Finally, we discern preliminary insights on the relationship and provides recommendations for how future studies may investigate the critical and complex relationship between user research and design creativity.

Orthotropic Hyperelastic Energy Functions for the Geometrically Nonlinear Simulation of Textile Membrane Structures

AbstractIn this contribution new orthotropic hyperelastic energy functions are proposed for the geometrically nonlinear simulation of woven textile membranes. The new models are investigated and compared with a competitive formulation with respect to mathematical characteristics, accuracy in representation of experimental data and their robustness in numerical simulations. Part of the models is polyconvex and thus, a physically meaningful and mathematically sound formulation is obtained. The models are adjusted to stress‐strain paths of a glass‐PTFE fabric under cyclic uniaxial and biaxial tension tests. Moreover, a new large scale experimental setup is presented which enables the study of the material behavior in real structural problems.

Modeling soil-crack–water–atmospheric interactions: a novel root water uptake approach to simulate the evaporation through cracked soil and experimental validation

Few studies numerically investigated evaporation through cracked soil using macro pore size distribution approach (conventional approach). In previous studies, the experimental results used for the simulation were usually obtained by evaporation from a very small mould. Moreover, those results are prone to size and boundary effects and can influence simulated soil moisture distribution around crack. In addition, difference between volumetric water contents (VWCs) computed using conventional approach and measured VWCs is relatively high. The main objective of the present study is to propose a new approach for simulating evaporation through cracked soil. The new approach draws analogy from root water uptake model, which includes a sink term. For validation, a large-scale experimental setup was designed and developed to obtain the experimental results by minimizing boundary effects. The experimental setup was instrumented to measure suction and VWC. Commercial finite element package “HYDRUS” was used to numerically solve (simulate) the Richards equation coupled with sink term. This study revealed that, root water uptake approach is appropriate for simulation of large reduction in VWCs under evaporation. Maximum difference between computed VWCs using conventional method and measured VWCs was observed to be 21%. Whereas, maximum difference between VWCs computed using novel root water uptake approach and measured VWCs was observed to be 16%. The proposed approach was able to predict soil moisture distributions more reasonably as it allows loss of water through cracks on soil surface.

Large-scale experimental evaluation of soil saturation effect on behaviour of buried pipes under operational loads

The behaviour of pipelines in unsaturated soil is fundamentally different from that of pipelines buried in dry or saturated soils. However, the effect of soil saturation on buried pipe behaviour has been overlooked in past research mainly due to the very limited large-scale experimental studies available. Most of the available studies on buried pipes in unsaturated soil are based on numerical modelling that analyses the pipe behaviour using a calibrated soil model developed on the basis of fundamental unsaturated soil characteristics. Investigations with such approaches may not be acceptable owing largely to unverified or complicated pipe–soil interactions and three-dimensional stress re-distributions. In this paper, the effect of soil saturation on buried pipe behaviour is investigated using a comprehensive large-scale experimental setup. A detailed methodology of large-scale testing, which was used to obtain pipe deformations as well as soil stresses with reference to a cast iron pipeline buried in low-plasticity clay under different soil saturation levels, is presented. The results obtained from large-scale experiments are compared with those of three-dimensional finite element analysis. Results produced in this paper reveal that the degree of water saturation of backfill soil can significantly affect the pipe deformation under internal and external loadings.

Influence of well pattern on gas recovery from methane hydrate reservoir by large scale experimental investigation

Natural gas hydrate is considered as a potential clean energy resource. Therefore, technology development for commercial gas recovery from natural gas hydrate is attracting extensive attention all over the world. The influence of well pattern on gas recovery from methane hydrate reservoir using depressurization combined with heat stimulation (D&H) method is firstly investigated in a large scale experimental set-up (PHS). The well patterns selected for hydrate decomposition are five-spot vertical wells (5 V), dual horizontal wells (2H), and trigonal horizontal wells (3H) in the experiments. The influences of well patterns on the production behaviors, the heat transfer characteristics, and the production efficiency are studied by the experiments. The experimental results indicate that the 5 V well pattern leads to the highest gas production rate (Rg), hydrate dissociation rate (Rd), and gas-water ratio, which is the optimal well pattern under the experimental condition in this work. However, by using the 5 V well pattern, the heat transfer rate rapidly decreases with the increase of the distance from hydrate dissociation interface to the injection well, which leads to the apparently decrease of the Rd in the later period of the heat stimulation stage. Because the decrease rates of the Rg and Rd by the 5 V well pattern is faster than those by the 3H and 2H well patterns, it can be predicted that if the well spacing increases, the 5 V well pattern may not be the optimal well pattern for gas recovery. In addition, the Rd using the 3H well pattern is higher than that by the 2H well pattern, because the decentralized heat injection in the 3H well pattern can enhance the heat convection in the sediment, further enhance the heat efficiency.

Free Hydraulic Jump Due to Parallel Jets

AbstractDue to construction, operation, and maintenance difficulties, usually installing very wide sluice gates in open channels is not recommended. Instead, multiple parallel gates have been used in such circumstances, which generate parallel jets. The free hydraulic jump established downstream of two vertical sluice gates with different openings was investigated theoretically and experimentally in this study. The ADV technique was used to record the flow velocity at the tailwater section of a rather large-scale experimental setup. The impact of highly non-uniform velocity distribution of the tailwater section was incorporated in the momentum formulation to develop a relationship for accurately determining the conjugate depth of such a practical case. It was indicated that the momentum correction factor plays a key role to accurately determining the conjugated depths, and it should not be neglected. Considering y0 as the upstream depth and y2 as the tailwater depth, the compiled data of the classical and...

Design of Wireless Sensor Nodes for Structural Health Monitoring Applications

Enabling low-cost distributed monitoring, wireless sensor networks represents an interesting solution for the implementation of structural health monitoring systems. This work deals with the design of wireless sensor networks for health monitoring of civil structures, specifically focusing on node design in relation to the requirements of different structural monitoring application classes. Design problems are analysed with specific reference to a large-scale experimental setup (the long-term structural monitoring of the Basilica S. Maria di Collemaggio, L’Aquila, Italy). Main limitations emerged are highlighted, and adopted solution strategies are outlined, both in the case of commercial sensing platform and of full custom solutions.

Natural convection in an air-filled cavity: Experimental results at large Rayleigh numbers

A large-scale experimental setup is built and instrumented. It consists in a 4 m-high cavity with a horizontal cross-section equal to 0.86 × 1.00 m². Two opposite vertical walls are heated and cooled down; other walls (lateral walls, ceiling and floor) are made of insulating medium covered with a thin and low-emissivity film designed to minimize radiative effects into the cavity. The temperatures of active walls are imposed, constant and equally distributed around the ambient temperature in order to reduce heat losses. The temperature difference between the hot and cold walls is chosen to respect the Boussinesq approximation. Under these assumptions, Rayleigh number values up to 1.2 × 10 11 (ΔT = 20 °C) can be obtained. The centre-symmetry is verified on the thermal stratification. Influence of the temperature difference and of wall emissivities on the stratification parameter (dimensionless vertical temperature gradient) is discussed. Velocity measurements allow the velocity field to be obtained and provide information on flows encountered in the cavity. Temperature measurements are also carried out in the whole cavity. In the paper, a complete experimental characterization is provided: airflow inside the cavity is analyzed and the Nusselt number along the hot and the cold wall is presented.

Separation of mixtures and distribution of a liquid on a structured packing in a large-scale model of a distillation column

A large-scale experimental setup is designed to study the hydrodynamic parameters and the mass-transfer efficiency in a countercurrent flow of mixtures of Freon R21 and Freon R114 on structured packings in a column 0.9 m in diameter. The study deals with the local and integral parameters of separation of the mixture, the degrees of nonuniformity of the flow rates and concentration distributions of the liquid and vapor phases over a cross section and on the column wall, and the pressure difference while varying the number of packing layers and their rotation angle. The mass-transfer processes while independently varying the liquid and vapor flow rates over wide ranges are also investigated. Experimental data are presented to illustrate the effect of the operating parameters on the height of an equivalent theoretical plate, the relative pressure difference, and the distributions of the local parameters of the flows.

A numerical approach for the study of glass furnace regenerators

Regenerative heat exchangers used in glass industry are complex systems owing to the transient nature of their operating cycle, as well as to the complexity of the heat exchange phenomena involved: aiding mixed convection during the cold period and combined presence of radiation and forced convection during the hot period. The present study describes an open method to simulate the behaviour of such regenerators. Preliminary results allowed us to validate our model in comparison with experimental and/or analytical data obtained on simple geometries. In a second step, a complete validation is proposed on a large scale experimental set-up which reproduces the exact behaviour of an industrial glass furnace regenerator. An original method based on the Boussinesq approximation with a “fictitious thermal expansion coefficient” was successfully introduced for this complete validation.

Experimental devices to determine snow avalanche basal friction and velocity profiles

Physical modelling is an important tool for obtaining insight into the internal flow structure of gravity currents such as snow avalanches, or, more practically, for estimating the dimensions of avalanche defense structures. We present a large-scale experimental setup, which allows the generation of avalanche-like gravity currents of snow under reproducible experimental conditions. The Weissfluhjoch chute is 34 m long, 2.5 m wide and can be run with up to 25 m 3 of natural snow. We present two types of optical velocity measurement devices based on the correlation method. We discuss their applicability to snow flows and perform an error analysis of the observed flow velocities. Furthermore, preliminary results of velocity profile measurements in the snow flow are presented. We also describe the experimental determination of the total dynamic basal friction force exerted on the ground. An effective dynamic friction coefficient is calculated.

The Pump-Driven Lateral-Thrust Unit with Ejector Augmentation

The idea of using cargo pumps to improve the low-speed maneuverability of tankers is evaluated. The main drawback of this system is the high kinetic energy loss in the jets, which results in an unfavorable thrust-to-installed-pump-power ratio. To improve the system, the exit velocity can be lowered, and the mass flow rate can be increased, by mounting the nozzles in contoured tunnels with open ends at both sides of the ship (ejector principle). Theory and experimental data derived from a large-scale experimental setup indicate that the performance of an ejector system for thrust generation is between the capability of a conventional screw-driven thruster and a radial pump-driven system with convergent nozzle.