Single Test Facility Research Articles

Characterization of patterns and variability in the dynamics of outdoor aquatic mesocosms: exploring the capabilities and challenges in data supporting aquatic system models

Aquatic mesocosms are complex test systems used within regulatory risk assessment of plant protection products. These model ecosystems allow researchers to capture interactions of multiple species under realistic environmental conditions. They enable assessment of direct and indirect effects of stressors at all trophic levels (i.e., from primary producers to secondary consumers) and impacts on ecosystem functions. Due to the limited ability to test the multitude of potential exposure scenarios, cross-linking aquatic mesocosm studies with virtual mesocosms, i.e., aquatic system models (ASMs), can serve to meet the demand for more environmental realism and ecological relevance in risk assessment. In this study, full control data sets from seven aquatic mesocosm studies conducted at a single test facility under GLP were analysed graphically and using descriptive statistics. Thereby, not only a comprehensive data base but also an insight into the species present, their dynamics over time, and variability in unchallenged mesocosms was observed. While consistency in dynamics could be discerned for physical and chemical parameters, variability was evident for several biological endpoints. This variability points to amplification of small differences over time as well as to stochastic processes. The outline of existing gaps and uncertainties in data leads to the estimation of what can be expected to be captured and predicted by ASMs.

Experimental verification of an accessible geographically distributed real‐time hybrid simulation platform

Real-time hybrid simulation (RTHS) has become a recognized methodology for isolating and testing complex, rate-dependent structural components and devices to understand their behavior and to evaluate their ability to improve the performance of structures exposed to severe dynamic loading. Although RTHS is efficient in its utilization of equipment and space compared with conventional testing techniques, the laboratory resources may not always be available in a single testing facility to conduct large-scale experiments. Consequently, distributed systems, capable of connecting multiple RTHS setups located at several geographically distributed facilities through appropriate information exchange, become desirable. This study presents a distributed RTHS (dRTHS) platform that enables the integration of geographically distributed physical and numerical components across the Internet. The essential capabilities needed to establish such a dRTHS platform are discussed, including the communication architecture, network components, and connection reliability. One significant challenge for conducting successful dRTHS is sustaining real-time communication between test sites. To accommodate realistic network delays due to variations in the Internet service, a Smith predictor-based delay compensation algorithm that includes a network time delay estimator is developed. A series of numerical and experimental studies is conducted to verify the platform and to quantify the impact of uncertainties present in a typical distributed system. Through an evaluation of the results, it is demonstrated that dRTHS is feasible for coupling laboratory capabilities and is a viable alternative to traditional testing techniques.

A Comparison of Spontaneous Tumors in Tg.rasH2 Mice in 26-week Carcinogenicity Studies Conducted at a Single Test Facility during 2004 to 2012 and 2013 to 2018.

This article presents the historical control data of spontaneous tumors in Tg.rasH2 published in 2013 (2004-2012) and compares and contrasts it to more recent data collected from 2013 to 2018, reporting differences in the average percentage incidences or incidence ranges as well as the incidence of new tumors. In 2013, we published a comprehensive review of spontaneous tumors in Tg.rasH2 mice used in 26-week carcinogenicity studies, which included data from control dose groups from 26 studies and a total of 710 mice per sex. The total database, now including the more recent data, has nearly doubled the number of animals, completing to date a total of 52 studies in males and 51 studies in females for a total of 1,615 male mice and 1,560 female mice, respectively. In this article, we compare the data collected from 2004 to 2012 against the data collected from 2013 to 2018 and the overall tumor incidence change.

Historical control data from 13-week repeated toxicity studies in Crj:CD (SD) rats

Reference ranges of standard experimental parameters are useful for comparisons in toxicology. The aim of this study was to collect data from 13-week repeated toxicity studies in Crl:CD (SD) rats, a strain widely used for toxicity and efficacy research, for establishing domestic reference values. Data on body weight, food consumption; urinalysis, hematological, and blood biochemical parameters; and organ weights were collected from 11 toxicity studies in 220 Crl:CD (SD) rats (110 males and 110 females). The studies had been performed at a single testing facility over the last 5 years and involved animals sourced from a single breeder. The findings were collated as means, standard deviations, percentages, and ranges. Urine volume, uterus weight, eosinophil, and basophil counts, and triglyceride, total bilirubin, and gamma-glutamyl transpeptidase levels showed standard deviations of 30% or more. These historical control data would help to interpret the effects of test substances in routine toxicity and efficacy studies.

The response of an overhead electrical power transmission line to two types of wind forcing

A study of an aeroelastic model of a single transmission line span and support structure was conducted at a length scaling of 1:100. Flexural rigidity of the lattice tower, mass and drag were scaled. In successive order, the experimental model was subjected to boundary layer and downdraft outflow wind forcing in a single test facility. The purpose of this study was to examine the difference in structural response to the two different types of wind forcing—this was motivated by an interest to understand why transmission line failures occur in downdraft winds. Although the fundamental mode of vibration was evident in the frequency-domain analysis, the simulation results indicated that the model generally responded quasi-statically to both types of wind forcing. Resonant dynamic response was less significant with downdraft outflow wind forcing than boundary layer wind forcing. Peak values of tower response to downdraft outflow wind forcing were significantly larger than that from boundary layer wind forcing. A substantial imbalance between peak load on the upstream and downstream conductors was observed for both types of wind forcing and was particularly severe for the downdraft outflow simulations.

TESTING ON A HIGH SPEED ELECTRO-RHEOLOGICAL CLUTCH

The design of a prototype ER clutch and its associated test facility have been described and sample results from the initial test programme are presented. The ER clutch shows considerable promise and outperforms various magnetic devices. Further clutch and ER fluid developments should increase these advantages. The test facility described provides a quick method for obtaining a wide range of important fluid properties from a single small quantity of fluid in a single test facility operating under realistic engineering conditions. The results reported emphasize the need for continuing ER fluid development to increase the ER shear stress, to reduce the viscosity of the ER fluid, to reduce the electronic to ER shear stress time delay, and to improve the durability of ER fluids.

Nb/sub 3/Sn conductor development programme for superconducting coils for the European Fusion Programme

The major part of the program involves the industrial fabrication of long lengths of full-size conductors and the manufacturing of test coils that will be thoroughly tested in a single test facility (TOSKA, at KfK Karlsruhe, Germany). A total of 3.5 km of 40-kA conductor is required to form circular model coils with an inner bore of 2 m and a peak field of over 13.5 T. Short (5-m) lengths of full-size 40-kA conductors have been manufactured. The present results on the industrial fabrication of 12-T, 40-kA cable-in-conduit conductors for the Next European Torus (NET) indicate that the machine design criteria can be satisfied and that the conductor is suitable for large-scale industrial fabrication.

Cavitation Control by Aeration of High-Velocity Jets

To prevent cavitation erosion, air may be introduced along the underside and sides of a jet before the jet comes in contact with downstream concrete surfaces. Model studies of chute offsets, air slots, and deflectors were conducted to determine methods to aerate the jet and provide recommendations for altering two existing structures and designing new structures. A single test facility was used to model existing structures at Palisades and Navajo Dams and proposed structures at Pueblo, Crystal, and Teton Dams. Wall air vent slots combined with a floor deflector were developed for use immediately downstream from the gate frames in the two existing structures. Wall and floor air vent offsets away from the flow at the end of the frame were developed for new structures. These investigations, supplemented by general tests, formed the basis for guidelines developed for design of future air-entraining devices to protect flow surfaces from cavitation erosion.