Required Separation Distance Research Articles

Lignite reduces odour from broiler farms without reducing production performance

An unavoidable consequence of chicken meat production is the generation of substantial quantities of spent litter. This poses several environmental and social challenges, as broiler farms become hotspots for odour emissions. The main source of odour from broiler litter is the microbial decomposition of organic material. Thus, lignite's previously shown capacity to reduce microbial activity in broiler litter was expected to reduce odour emissions from broiler housing. The effect of lignite on odour emission rate (OER) (ou/s) was investigated using dynamic olfactometry over two consecutive summer broiler grow-out cycles in Victoria, Australia, with lignite applied at 3.5 kg/m2. The air quality dispersion model, AERMOD, was used to investigate how lignite's effect on OER influenced the predicted odour dispersion distances and concentrations in the context of various Australian regulatory requirements. Additionally, the effect of lignite on bird production performance was also determined. This study showed that lignite reduced the OER from commercial broiler housing by an average of 56% over both grow-outs. This effect was observed for the duration of the trial. The observed reduction in OER reduced the required separation distances by 44–53% according to the state odour criteria for Victoria, New South Wales, Queensland and South Australia. There were no observed differences in feed conversion ratio, bird live weight or mortality throughout either grow-out. This study demonstrated the capacity of lignite to reduce odour emissions from commercial broiler housing without reducing bird production performance.

Co-Channel Compatibility Analysis of IMT Networks and Digital Terrestrial Television Broadcasting in the Frequency Range 470-694 MHz Based on Monte Carlo Simulation.

According to Resolution 235 adopted during the World Radiocommunication Conference 2015 (WRC-15) and the preliminary agenda item 1.5 of WRC-2023, the International Telecommunication Union Radiocommunication Sector (ITU-R) has been entrusted to carry out sharing and compatibility studies between broadcasting and mobile services in the frequency range 470-694 MHz in Region 1. This study specifically focuses on evaluating electromagnetic compatibility in potential co-channel sharing scenarios between Digital Terrestrial Television Broadcasting (DTTB) and International Mobile Telecommunications (IMT) systems within the 470-694 MHz frequency band that may arise in the foreseeable future. To assess the conditions for coexistence, a Monte Carlo simulation method implemented through the SEAMCAT software version 5.4.2 is employed, examining six potential interference scenarios. The simulation results yield the minimum coordination distance required between IMT and DTTB services in the 470-694 MHz band based on the protection criteria to ensure harmonious coexistence while maintaining satisfactory performance. Furthermore, the study investigates the impact of various factors such as transmitter power, antenna heights, coverage radius, antenna discrimination, and antenna tilt angle on the separation distances. The focus lies primarily on critical interference scenarios across neighboring countries' borders. The simulation outcomes confirm that sharing the same frequency band between IMT and DTTB networks would result in significant mutual interference. Nevertheless, carefully analyzing diverse parameters and assumptions helped provide recommendations to reduce the required separation distances. These findings are valuable for broadcasters, mobile operators, and regulators in establishing the technical coexistence conditions for DTTB and IMT in the new band.

Structural Pounding Effect on the Seismic Performance of a Multistorey Reinforced Concrete Frame Structure

During intense ground motion excitations, the pounding between adjacent buildings may result in extensive structural damage. Despite the provision of regulations regarding the minimum separation gap required to prevent structural collisions, the majority of existing structures are poorly separated. The modern seismic design and assessment of structures are based on the definition of acceptable response levels in relation to the intensity of seismic action, which is usually determined by an acceptable probability of exceedance. From this point of view, the seismic performance of a typical eight-storey reinforced concrete (RC) frame structure is evaluated in terms of pounding. In particular, the performance is evaluated using six different separation gap distances as a fraction of the EC8 minimum distance. As the height of the adjacent structure affected the required separation distance, the examined RC structure was assumed to interact with four idealized rigid structures of one to four storeys. The typical storey height was equal between the examined structures; therefore, collision could occur at the diaphragm level. To this end, incidental dynamic analyses (IDAs) were performed, and the fragility curves for different limit states were obtained for each case. Finally, the seismic fragility was combined with the hazard data to evaluate the seismic performance probabilistically.

Safety considerations for autonomous, modular robotics in aerospace manufacturing.

Industrial robots are versatile machines that can be used to implement numerous tasks. They have been successful in applications where-after integration and commissioning-a more or less static and repetitive behaviour in conjunction with closed work cells is sufficient. In aerospace manufacturing, robots still struggle to compete against either specialized machines or manual labour. This can be attributed to complex or custom parts and/or small batch sizes. Here, applicability of robots can be improved by enabling collaborative use-cases. When fixed protective fences are not desired due to handling problems of the large parts involved, sensor-based approaches like speed and separation monitoring (SSM) are required. This contribution is about how to construct dynamic volumes of space around a robot as well as around a person in the way that their combination satisfies required separation distance between robot and person. The goal was to minimize said distance by calculating volumes both adaptively and as precisely as possible given the available information. We used a voxel-based method to compute the robot safety space that includes worst-case breaking behaviour. We focused on providing a worst-case representation considering all possible breaking variations. Our approach to generate the person safety space is based on an outlook for 2D camera, AI-based workspace surveillance.

Effective Gap Size Index for Determination of Optimum Separation Distance Preventing Pounding between Buildings during Earthquakes

Seismic excitations may lead to collisions between adjacent civil engineering structures, causing major damage. In this paper, an effective equation for calculating the gap size index is proposed so as to provide the optimum separation distance preventing structural pounding during different earthquakes. Evaluation of the best prediction of the required separation distance between two adjacent buildings was carried out by using the lumped mass multi-degrees of freedom models of structures. A special computer program was used to perform dynamic analyses in order to confirm the accuracy of the proposed formula. For this purpose, several different models of buildings with various properties under different earthquake excitations were analyzed. The results of the study clearly show that the proposed formula for the gap size index (based on vibration periods and damping ratios of buildings) is effective and it allows us to calculate the optimum separation between adjacent structures preventing their pounding during different earthquakes.

Required separation distance for reinforced concrete with seismic pounding potential

Required separation distance for reinforced concrete with seismic pounding potential

Design of Compact Huygens’ Metasurface Pairs With Multiple Reflections for Arbitrary Wave Transformations

Huygens' metasurfaces have demonstrated a remarkable potential to perform wave transformations within a subwavelength region. In particular, omega-bianisotropic Huygens' metasurfaces have allowed for the passive implementation of any wave transformation that conserves real power locally. Previous reports have also shown that Huygens' metasurface pairs are capable of realizing transformations that break the local power conservation requirement by redistributing the total power, while the wave propagates between the two metasurfaces. However, the required separation distance overshadows the low-profile characteristics of the individual metasurfaces and leads to bulky designs, especially for lower frequencies. In this work, we develop a method of designing omega-bianisotropic Huygens' metasurface pairs, relying on a point-matching process of the real power at the two metasurfaces. We highlight the versatility of our method by presenting two variations of the configuration, depending on whether the electromagnetic source is located within or outside the metasurface pair. Based on the examples of a cylindrical-wave to plane-wave transformation and a beam expander, we examine the impact of multiple reflections, as a way to overcome the size limitations and design compact structures. Moreover, we explore possible beamforming applications through an example of a Taylor-pattern antenna with a single feed-point between the two metasurfaces.

Are Empirical Equations an Appropriate Tool to Assess Separation Distances to Avoid Odour Annoyance?

Annoyance due to environmental odour exposure is in many jurisdictions evaluated by a yes/no decision. Such a binary decision has been typically achieved via odour impact criteria (OIC) and, when applicable, the resultant separation distances between emission sources and residential areas. If the receptors lie inside the required separation distance, odour exposure is characterised with the potential of causing excessive annoyance. The state-of-the-art methodology to determine separation distances is based on two general steps: (i) calculation of the odour exposure (time series of ambient odour concentrations) using dispersion models and (ii) determination of separation distances through the evaluation of this odour exposure by OIC. Regarding meteorological input data, dispersion models need standard meteorological observations and/or atmospheric stability typically on an hourly basis, which requires expertise in this field. In the planning phase, and as a screening tool, an educated guess of the necessary separation distances to avoid annoyance is in some cases sufficient. Therefore, empirical equations (EQs) are in use to substitute the more time-consuming and costly application of dispersion models. Because the separation distance shape often resembles the wind distribution of a site, wind data should be included in such approaches. Otherwise, the resultant separation distance shape is simply given by a circle around the emission source. Here, an outline of selected empirical equations is given, and it is shown that only a few of them properly reflect the meteorological situation of a site. Furthermore, for three case studies, separation distances as calculated from empirical equations were compared against those from Gaussian plume and Lagrangian particle dispersion models. Overall, our results suggest that some empirical equations reach their limitation in the sense that they are not successful in capturing the inherent complexity of dispersion models. However, empirical equations, developed for Germany and Austria, have the potential to deliver reasonable results, especially if used within the conditions for which they were designed. The main advantage of empirical equations lies in the simplification of the meteorological input data and their use in a fast and straightforward approach.

Escape responses of terrestrial and aquatic birds to drones: Towards a code of practice to minimize disturbance

Abstract Advances in human technology can lead to widespread and rapid increases in interactions between wildlife and potentially disturbing stimuli. The recreational use of drones is widespread and increasing, yet laws and codes of practice which aim to manage deleterious impacts (e.g. negative interactions with wildlife) are reactionary, unscientific and inadequate. One prominent potential negative effect of drones interacting with birds is disturbance; the disruption of normal states caused by responses such as escape. We measure avian escape responses to an approaching drone (n = 561 across 22 species) to inform the development of a code of practice to manage drone‐induced disturbance. Approaches were made at a relatively high and low altitude (10 and 4 m), and at different take‐off distances, both of which are candidate prescriptions for a code of practice. Flight‐initiation distance varied between species, but not between the altitudes tested. The probability of eliciting an escape response was high, and 14.6% higher at the lower altitude (at which 88.4% of overflies resulted in an escape response). Our response rates (from terrestrial and aquatic species) are higher than those reported for different birds in other places, most of which were water or seabirds. The probability of a drone take‐off in itself eliciting a response was low (<20%) when the drone take‐off was >40 m away, and decreased further with increasing distance from birds, with no escapes occurring >120 m. Policy implications. For our sample, no drone take‐off closer than 100 m, and no flight within 100 m would eliminate the vast majority of escape responses by birds. Required separation distances between drones and wildlife may exceed those required for other human activities, such as for walkers.

Stochastic Analysis of Adjacent Structures Subjected to Structural Pounding under Earthquake Excitation

Seismic pounding occurs as a result of lateral vibration and insufficient separation distance between two adjacent structures during earthquake excitation. This research aims to evaluate the stochastic behavior of adjacent structures with equal heights under earthquake-induced pounding. For this purpose, many stochastic analyses through comprehensive numerical simulations are carried out. About 4.65 million time-history analyses were carried out over the considered models within OpenSees software framework. Various separation distances effects are also studied. The response of considered structures is obtained by means of Hertzdamp contact element. The models have been excited using 25 earthquake records with different peak ground accelerations. The probability of collision between neighboring structures has been evaluated. An efficient combination of analytical and simulation techniques is used for the calculation of the separation distance under the assumptions of non-linear elasto-plastic behavior for the structures. The results obtained through Monte Carlo simulations show that use of the current provision’s rule may significantly overestimate or underestimate the required separation distance, depending on the natural vibration periods of adjacent buildings. Moreover, based on the results, a formula is developed for stochastic assessment of required separation distance.

Assessment on required separation length between adjacent bridge segments to avoid pounding

This paper presents a probability-based method, based on the design required separation length, to evaluate the likelihood beyond the required separation length of pounding of bridge structures under seismic excitations. Firstly, based on the stochastic vibration theory, the probabilistic pounding model was developed to model the influence of different seismic intensity levels and local soil condition on determination of the required separation gap between bridge segments. Then, the varying relationship between exceedance probability of pounding and seismic intensity measure (PGA) was derived. The proposed probability-based pounding evaluation approach was applied to a real bridge for predicting the pounding occurrence under various seismic intensity levels, along with the finite element model of the bridge pounding system built in ANSYS. Finally the pounding risk assessment beyond the required separation length of the bridge structure was conducted and presented based on the required separation distance. The results of this study delivered explicit and direct specifications and guidelines for seismic pounding design of bridges with different separation gap.

Spectrum-Sharing Method for Co-Existence Between 5G OFDM-Based System and Fixed Service

This study investigates the co-existence of fifth generation (5G) mobile communication systems and fixed service (FS) in the 28-GHz band through the utilization and modification of an existing spectrum-sharing method known as the advanced minimum coupling loss (A-MCL) model. The proposed model is based on the power spectral density (PSD) overlap between the 5G orthogonal frequency-division multiplexing (OFDM)-based system and the FS. Spectrum-sharing studies typically need 5G parameters, such as the spectrum emission mask (SEM); however, no such information is available for the new system to achieve accurate results. The proposed model is suitable for spectrum-sharing studies between 5G and other wireless systems without the need for the 5G SEM. Moreover, the existing model is implemented in a new application (i.e., 5G) in the 28-GHz band with different 5G bandwidths. Furthermore, the FS parameters and its frequency allocation are selected based on the Canadian standards to obtain preliminary results for the co-existence between the 5G system and the FS. Results show that co-existence is feasible when certain distances are applied, especially with higher 5G bandwidths (such as 0.5 and 1 GHz) when the 5G system acts as an interferer. In addition, the antenna position plays a major role in reducing the required separation distances between the victim receiver and the interfering transmitter. This model can be used for any future mobile generation such as the sixth generation (6G) mobile system if its PSD is known. This study is concurrent with the worldwide spectrum-sharing studies requested by the International Telecommunication Union for WRC-19.

Methodology to estimate minimum required separation distance between vehicle and bicycle when overtaking

Methodology to estimate minimum required separation distance between vehicle and bicycle when overtaking

Two decomposition algorithms for solving a minimum weight maximum clique model for the air conflict resolution problem

In this paper, we tackle the conflict resolution problem using a new variant of the minimum-weight maximum-clique model. The problem involves identifying maneuvers that maintain the required separation distance between all pairs of a set of aircraft while minimizing fuel costs. We design a graph in which the vertices correspond to a finite set of maneuvers and the edges connect conflict-free maneuvers. A maximum clique of minimal weight yields a conflict-free situation that involves all the aircraft and minimizes the costs induced. The model uses a different cost structure compared to classical clique search problems: the costs of the vertices cannot be determined a priori, since they depend on the vertices in the clique. We formulate the problem as a mixed integer linear program. Since the modeling of the aircraft dynamics and the computation of trajectories is separated from the solution process, our mathematical framework is valid for any hypotheses on the aircraft dynamics and any choice of the available maneuvers. In particular, the aircraft can perform dynamic velocity, heading, and flight-level changes. To solve instances involving a large number of aircraft spread over several flight levels, we introduce two decomposition algorithms. The first is a sequential mixed integer linear programming procedure that iteratively refines the discretization of the maneuvers to yield a trade-off between computational time and cost. The second is a large neighborhood search heuristic that uses the first procedure as a subroutine. The best solutions for the available set of maneuvers are obtained in less than ten seconds for instances with up to 250 aircraft randomly allocated to bisten flight levels.

Analysis of seismic pounding between adjacent buildings

Seismic poundings between inadequately separated buildings have been observed in most previous major earthquakes. Pounding usually caused local damage around the impacting areas, and in extreme cases, collapse of the building structures. AS1170.4-2007 requires the separation between adjacent buildings to be at least 1% of the building height to avoid seismic pounding. This article presents intensive numerical simulations to examine the adequacy of this specification to preclude seismic pounding between RC frame structures under design earthquake loading defined for Perth, and the effects of pounding, if it occurs, on structural responses. It is found that AS 1170.4-2007 in general provides a conservative approach for determining the required separation distances to avoid pounding. Intensive numerical simulations are also carried out to study the effects of pounding on structural responses. Two adjacent RC frame models of 5-storey and 10-storey with different separation gaps and fundamental period ratios are considered. Impact forces, displacements and shear forces of the two frame structures with or without pounding subjected to ground motions corresponding to different site conditions are calculated. The influences of seismic pounding on frame structures are discussed.

A comparison of modelling approaches to assess the transmission of pathogens between Scottish fish farms: The role of hydrodynamics and site biomass

Scotland is the largest Atlantic salmon (Salmo salar) producer in the EU with an output of over 150,000t, contributing over £500 million annually towards the economy. Production continues to increase, predominantly due to the increase in output per farm and reduction in losses due to infectious diseases. Farms are grouped within disease management areas whose boundaries are defined by where the closest pair of farms is separated by more than twice the tidal excursion distance (TE) Tidal excursion is defined as 7.2km in mainland Scotland, or 3.6km in the Shetland Islands). The majority of salmon farms are located within relatively sheltered inshore areas where non-tidal advective current speed is minimal. However there is an aspiration for offshore production where it might be possible to increase stocking levels and where current speeds will be greater so TE models could break down.Separation distances whereby farms would avoid infection risk were obtained using an analytical, discrete-time Susceptible-Exposed-Infectious-Recovered (SEIR) model coupled with a hydrodynamic transport expression representing transmission of pathogenic agents between fish farms. The model incorporated transmission, expression and recovery parameters as well as pathogen shedding and decay. The simplified hydrodynamic model incorporated residual advection, tidal advection and turbulent diffusion elements. The obtained separation distances were compared to a computationally intensive, numerical model and were demonstrated to be comparable, although the analytical model underestimated the variation within the transmission distances.Applying characteristics for a robust pathogen, infectious pancreatic necrosis virus type (IPNV-type), and less robust pathogens such as infectious salmon anaemia virus type (ISAV-type) and Aeromonas salmonicida type (AS-type) pathogens, it was possible to obtain separation distances whereby farms avoided infection. Simulation outputs indicated that separation distances should increase to avoid disease as farm size and current speed increase. The more conserved IPNV-type pathogen required separation distances of hundreds of kilometres, AS-type required tens of kilometres, whilst the distances for ISAV-type were within the scale of the current DMAs, that were developed for ISAV control. However, should production be moved to areas of faster moving currents and increased farm production the current disease management area principles might need readdressing.

Determining appropriate wind turbine setback distances: Perspectives from municipal planners in the Canadian provinces of Nova Scotia, Ontario, and Quebec

This paper uses a series of interviews to investigate how municipal planners in three Canadian provinces (Nova Scotia, Quebec, and Ontario) influence setbacks that regulate appropriate locations for wind turbines. Setbacks are provisions in local land use policies that dictate required separation distances between wind turbines and other land uses. Results of the study indicate that planners are not using a consistent method to ascertain appropriate distances and are often constrained by a lack of experience, resources, and expertise. These findings have important implications for wind energy regulation. Setbacks are intended to reasonably protect the public from the impacts of wind turbines, while allowing for some development. Municipalities in Canada may be best placed to consider local impacts of wind power, but the challenges identified raise concerns about potential arbitrariness. Setbacks that are unjustifiably high can unnecessarily close off territory and limit the ability to reach renewable energy targets. Taking regulatory power away from municipalities, as has happened in Ontario, can facilitate achievement of provincial targets, but may also increase opposition to projects at the local level.

Influence of ground motion spatial variation, site condition and SSI on the required separation distances of bridge structures to avoid seismic pounding

AbstractIt is commonly understood that earthquake ground excitations at multiple supports of large dimensional structures are not the same. These ground motion spatial variations may significantly influence the structural responses. Similarly, the interaction between the foundation and the surrounding soil during earthquake shaking also affects the dynamic response of the structure. Most previous studies on ground motion spatial variation effects on structural responses neglected soil–structure interaction (SSI) effect. This paper studies the combined effects of ground motion spatial variation, local site amplification and SSI on bridge responses, and estimates the required separation distances that modular expansion joints must provide to avoid seismic pounding. It is an extension of a previous study (Earthquake Engng Struct. Dyn. 2010; 39(3):303–323), in which combined ground motion spatial variation and local site amplification effects on bridge responses were investigated. The present paper focuses on the simultaneous effect of SSI and ground motion spatial variation on structural responses. The soil surrounding the pile foundation is modelled by frequency‐dependent springs and dashpots in the horizontal and rotational directions. The peak structural responses are estimated by using the standard random vibration method. The minimum total gap between two adjacent bridge decks or between bridge deck and adjacent abutment to prevent seismic pounding is estimated. Numerical results show that SSI significantly affects the structural responses, and cannot be neglected. Copyright © 2010 John Wiley & Sons, Ltd.

Required separation distance between decks and at abutments of a bridge crossing a canyon site to avoid seismic pounding

AbstractMajor earthquakes in the past indicated that pounding between bridge decks may result in significant structural damage or even girder unseating. With conventional expansion joints, it is impossible to completely avoid seismic pounding between bridge decks, because the gap size at expansion joints is usually not big enough in order to ensure smooth traffic flow. With a new development of modular expansion joint (MEJ), which allows a large joint movement and at the same time without impeding the smoothness of traffic flow, completely precluding pounding between adjacent bridge decks becomes possible. This paper investigates the minimum total gap that a MEJ must have to avoid pounding at the abutments and between bridge decks. The considered spatial ground excitations are modelled by a filtered Tajimi‐Kanai power spectral density function and an empirical coherency loss function. Site amplification effect is included by a transfer function derived from the one‐dimensional wave propagation theory. Stochastic response equations of the adjacent bridge decks are formulated. The effects of ground motion spatial variations, dynamic characteristics of the bridge and the depth and stiffness of local soil on the required separation distance are analysed. Soil–structure interaction effect is not included in this study. The bridge response behaviour is assumed to be linear elastic. Copyright © 2009 John Wiley & Sons, Ltd.

Vortex wake mitigation of an airfoil with winglets by active rudders

AbstractThe wake vortex hazard and the required separation distances between aircraft at airports constitute an impediment to the growth of air traffic at major hubs. One approach to reduce separation distances is the exploitation of the inherent instability in vortex systems, leading to an accelerated breakdown. In this paper we show the impact of excitation by different control surfaces on the stability behavior of the wake of a rectangular wing with winglets. The experiment shows that the excitation through winglet rudders and ailerons yields the best results. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)