Scale dependency in the hydromorphological control of a stream ecosystem functioning

Physical habitat degradation is prevalent in river ecosystems. Although still little is known about the ecological consequences of altered hydromorphology, understanding the factors at play can contribute to sustainable environmental management. In this study we aimed to identify the hydromorphological features controlling a key ecosystem function and the spatial scales where such linkages operate. As hydromorphological and chemical pressures often occur in parallel, we examined the relative importance of hydromorphological and chemical factors as determinants of leaf breakdown. Leaf breakdown assays were investigated at 82 sites of rivers throughout the French territory. Leaf breakdown data were then crossed with data on water quality and with a multi-scale hydro- morphological assessment (i.e. upstream catchment, river segment, reach and habitat) when quantitative data were available. Microbial and total leaf breakdown rates exhibited differential responses to both hydromorphological and chemical alterations. Relationships between the chemical quality of the water and leaf breakdown were weak, while hydromorphological integrity explained independently up to 84.2% of leaf breakdown. Hydrological and morphological parameters were the main predictors of microbial leaf breakdown, whereas hydrological parameters had a major effect on total leaf breakdown, particularly at large scales, while morphological parameters were important at smaller scales. Microbial leaf breakdown were best predicted by hydromorphological features defined at the upstream catchment level whereas total leaf breakdown were best predicted by reach and habitat level geomorphic variables. This study demonstrates the use of leaf breakdown in a biomonitoring context and the importance of hydromorphological integrity for the functioning of running water. It provides new insights for envi- ronmental decision-makers to identify the management and restoration actions that have to be un- dertaken including the hydromorphogical features that should be kept in minimal maintenance to support leaf breakdown

A network approach to mechanisms and machines: some lessons learned

This is essentially a review paper describing progress made in treating mechanisms and machines as networks. Some of the terminology that is helpful to this approach is explained. Relevant elements of graph theory are mentioned. The original aim was to find a robust procedure for finding the instantaneous relative motion of all pairs of bodies within a kinematic chain. The manner in which this was achieved produced several other results that have found unanticipated applications. These are mentioned and publications are cited. Lessons have been learned and these are discussed in Section 11

A network approach to mechanisms and machines: Some lessons learned

This article was published in the journal, Mechanism and Machine Theory [© Elsevier] and the definitive version is available at: http://dx.doi.org/10.1016/j.mechmachtheory.2014.09.006This is essentially a review paper describing progress made in treating mechanisms and machines as networks. Some of the terminology that is helpful to this approach is explained. Relevant elements of graph theory are mentioned. The original aim was to find a robust procedure for finding the instantaneous relative motion of all pairs of bodies within a kinematic chain. The manner in which this was achieved produced several other results that have found unanticipated applications. These are mentioned and publications are cited. Lessons have been learned and these are discussed in Section 11

Controlled Experiments of Hillslope Coevolution at the Biosphere 2 Landscape Evolution Observatory: Toward Prediction of Coupled Hydrological, Biogeochemical, and Ecological Change

Understanding the process interactions and feedbacks among water, porous geological media, microbes, and vascular plants is crucial for improving predictions of the response of Earth’s critical zone to future climatic conditions. However, the integrated coevolution of landscapes under change is notoriously difficult to investigate. Laboratory studies are limited in spatial and temporal scale, while field studies lack observational density and control. To bridge the gap between controlled laboratory and uncontrollable field studies, the University of Arizona built a macrocosm experiment of unprecedented scale: the Landscape Evolution Observatory (LEO). LEO comprises three replicated, heavily instrumented, hillslope-scale model landscapes within the environmentally controlled Biosphere 2 facility. The model landscapes were designed to initially be simple and purely abiotic, enabling scientists to observe each step in the landscapes’ evolution as they undergo physical, chemical, and biological changes over many years. This chapter describes the model systems and associated research facilities and illustrates how LEO allows for tracking of multiscale matter and energy fluxes at a level of detail impossible in field experiments. Initial sensor, sampler, and soil coring data are already providing insights into the tight linkages between water flow, weathering, and microbial community development. These interacting processes are anticipated to drive the model systems to increasingly complex states and will be impacted by the introduction of vascular plants and changes in climatic regimes over the years to come. By intensively monitoring the evolutionary trajectory, integrating data with mathematical models, and fostering community-wide collaborations, we envision that emergent landscape structures and functions can be linked, and significant progress can be made toward predicting the coupled hydro-biogeochemical and ecological responses to global change

Landscape-scale prediction of forest productivity by hyperspectral remote sensing of canopy nitrogen

Foliar nitrogen concentration represents a direct and primary link between carbon and nitrogen cycling in terrestrial ecosystems. Although foliar N is used by many ecosystem models to predict leaf-level photosynthetic rates, it has rarely been examined as a direct scalar to stand-level carbon gain. Significant improvements in remote sensing detector technology in the list decade now allow for improved landscape-level estimation of the biochemical attributes of forest ecosystems. In this study, relationships among forest growth (aboveground net primary productivity (ANPP) and aboveground woody biomass production (AWBP)), canopy chemistry and structure, and high resolution imaging spectrometry were examined for 88 long-term forest growth inventory plots maintained by the USDA Forest Service within the 300,000 ha White Mountain National Forest, New Hampshire. Analysis of plot-level data demonstrates a highly predictive relationship between whole canopy nitrogen concentration (g/100 g) and aboveground forest productivity (ANPP: R2 = 0.81, p \u3c 0.000; AWBP: R 2 = 0.86, p \u3c 0.000) within and among forest types. Forest productivity was more strongly related to mass-based foliar nitrogen concentration than with either total canopy N or canopy leaf area. Empirical relationships were developed among spectral data from the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) and field-measured canopy nitrogen concentration (mass basis). Results of this analysis suggest that hyperspectral remote sensing can be used to accurately predict foliar nitrogen concentration, by mean of a full-spectrum partial least squares calibration method, both within a single scene (R2 = 0.84, SECV = 0.23) and across a large number of contiguous images (R2 = 82, SECV = 0.25), as well as between image dates (R2 = 0.69, SECV = 0.25). Forest productivity coverages for the White Mountain National Forest were developed by estimating whole canopy foliar N concentration from AVIRIS spectral response. Image spatial patterns broadly reflect the distribution of functional types, while fine scale spatial variation results from a variety of natural and anthropogenic factors. This approach provides the potential to increase the accuracy of forest growth and carbon gain estimates at the landscape level by providing information at the fine spatial scale over which environmental characteristics and human land use vary

A Simplified Rainfall-Streamflow Network Model on Multivariate Regression Analysis for Water Level Forecasting in Klong Luang (KGT.19 Station) Sub-watershed, Chon Buri Province, Thailand

A simplified rainfall-streamflow network model based on multivariate linear regression (MLR) analysis has been proposed. To determine significant coefficients of streamflow network, eleven MLR models were examined. The study’s three objectives were 1) to develop a novel a mathematical model based on MLR analysis for forecasting optimal water levels; 2) to determine the most significant coefficient of rainfall-streamflow network among in the area of interest in the vicinity of Klong Luang sub-watershed KGT.19 station; and 3) to apply the optimal MLR model for water level and flood forecasting maps in Klong Luang Sub-watershed. We used Geographic Information System (GIS) and Remotely Sensed Data (RS) data recorded from Klong Luang (KGT.19 Station) sub-watershed, and Phanat Nikhom, Chonburi, Ban Bueng and Phan Thong districts, in Chonburi Province, Thailand. The findings indicated that the MLR based Model No. 8 is the most applicable and effective. The proposed model also could be applied in water level forecasting, water resource management, flood hazard planning, and flood early warning

The resilience of urban design to pluvial flood

Resilient urban design has become an essential concern for cities needing to withstand the increasing number of natural and human-induced disasters. Yet cities and their infrastructures are becoming more vulnerable and threatened as flood protection measurements are still following the same line of thinking in terms of nature resistance. The conventional structures of flood protection are increasingly questioned amongst academics, decision makers and communities particularly since many cases of failure around the world. New approaches for characterising the resilience of urban design are urgently needed and worth investing in on local and regional scales. This research calls for a practical approach to investigate the resilience potential of urban design as a man-made solution and to consider the adjacent ecology as the natural surroundings. This aims to develop an ecologically compliant urban design approach that contributes to the mitigation of flood consequences with other infrastructure solutions. This research aims to shed light on the potential of ecological urban design to demonstrate a resilient urban form that can cope with the escalating flood threats in the Muscat area in Oman. A shift in thinking is required, towards a paradigm that calls for a breakaway from the closely confined resistance approach to the much more tolerable concept of living with the reality of water dominance. This is going to be realised by carrying out in-depth analysis of the ecological system services along with the physical aspects of urban design

Reynolds Number Effects on Thrust Coefficients and PIV for Flapping Wing Micro Air Vehicles

For the last several years the Air Force Institute of Technology (AFIT) has conducted research in aerodynamics for flapping wing micro air vehicles (MAVs). The focus of this research was to augment this effort by measuring thrust, velocity, and torque in tanks of water and glycerin using a scale and a reaction torque cell. The results for different flapping mechanisms are compared to a rotating propeller with the goal of elucidating the design trade space between rotorcraft and flapping wings at Reynolds numbers less than 100,000. In addition, flow visualization and quantitative velocity data were captured in the wake of the flapping wing. One flapping-wing mechanism was designed to incorporate a coupled 4-bar planar and 4-bar spatial linkage system to prescribe motion which included both flapping and rotation. Thrust and velocity data were found to follow the general trends for a flapping wing with passive rotation. The passive rotation angle setting was found to alter thrust and velocity patterns

Multi-scale assessment of human-induced changes to Amazonian instream habitats

Context Land use change and forest degradation have myriad effects on tropical ecosystems. Yet their consequences for low-order streams remain very poorly understood, including in the world´s largest freshwater basin, the Amazon. Objectives Determine the degree to which physical and chemical characteristics of the instream habitat of low-order Amazonian streams change in response to past local- and catchment-level anthropogenic disturbances. Methods To do so, we collected field instream habitat (i.e., physical habitat and water quality) and landscape data from 99 stream sites in two eastern Brazilian Amazon regions. We used random forest regression trees to assess the relative importance of different predictor variables in determining changes in instream habitat response variables. Results Multiple drivers, operating at multiple spatial scales, were important in determining changes in the physical habitat and water quality of the sites. Although we found few similarities in modelled relationships between the two regions, we observed non-linear responses of specific instream characteristics to landscape change; for example 20 % of catchment deforestation resulted in consistently warmer streams. Conclusions Our results highlight the importance of local riparian and catchment-scale forest cover in shaping instream physical environments, but also underscore the importance of other land use changes and activities, such as road crossings and upstream agriculture intensification. In contrast to the property-scale focus of the Brazilian Forest code, which governs environmental regulations on private land, our results reinforce the importance of catchment-wide management strategies to protect stream ecosystem integrity

A Parametric Study of Actuator Requirements for Active Turbine Tip Clearance Control of a Modern High Bypass Turbofan Engine

The efficiency of aircraft gas turbine engines is sensitive to the distance between the tips of its turbine blades and its shroud, which serves as its containment structure. Maintaining tighter clearance between these components has been shown to increase turbine efficiency, increase fuel efficiency, and reduce the turbine inlet temperature, and this correlates to a longer time-on-wing for the engine. Therefore, there is a desire to maintain a tight clearance in the turbine, which requires fast response active clearance control. Fast response active tip clearance control will require an actuator to modify the physical or effective tip clearance in the turbine. This paper evaluates the requirements of a generic active turbine tip clearance actuator for a modern commercial aircraft engine using the Commercial Modular Aero-Propulsion System Simulation 40k (C-MAPSS40k) software that has previously been integrated with a dynamic tip clearance model. A parametric study was performed in an attempt to evaluate requirements for control actuators in terms of bandwidth, rate limits, saturation limits, and deadband. Constraints on the weight of the actuation system and some considerations as to the force which the actuator must be capable of exerting and maintaining are also investigated. From the results, the relevant range of the evaluated actuator parameters can be extracted. Some additional discussion is provided on the challenges posed by the tip clearance control problem and the implications for future small core aircraft engines