Bi-criterion optimisation for configuring an assembly supply chain using Pareto ant colony meta-heuristic

An assembly supply chain (SC) is composed of stages that provide the components, assemble both sub-assemblies and final products, and deliver products to the customer. The activities carried out in each stage could be performed by one or more options, thus the decision-maker must select the set of options that minimises the cost of goods sold (CoGS) and the lead time (LT), simultaneously. In this paper, an ant colony-based algorithm is proposed to generate a set of SC configurations using the concept of Pareto optimality. The pheromones are updated using an equation that is a function of the CoGS and LT. The algorithm is tested using a notebook SC problem, widely used in literature. The results show that the ratio between the size of the Pareto Front computed by the proposed algorithm and the size of the one computed by exhaustive enumeration is 90%. Other metrics regarding error ratio and generational distance are provided as well as the CPU time to measure the performance of the proposed algorithm.This work was partially supported by the Spanish Ministerio de Ciencia e Innovación, under the project “Gestión de movilidad eficiente y sostenible, MOVES” with grant reference TIN2011-28336

Inspection and repair considerations for downtime assessment of seismically isolated buildings

Data availability: Data will be made available on request.Copyright © 2022 The Authors. This paper investigates the seismic downtime of seismically isolated buildings with steel moment or braced frames designed by the procedures of ASCE/SEI 7–16. The seismic isolation systems considered in this study are comprised of triple or double friction pendulum isolation bearings with and without moat walls. The seismic downtime is calculated from the damage to structural components and non-structural components, demolition and collapse of buildings. The downtime components (repair and inspection) are defined, and mathematical expressions are provided for the computation of downtime fragility curves, expected annual downtime, and economic losses due to the expected annual downtime. The procedure is then implemented using the results of nonlinear response history analysis from previous studies by the first author. The study demonstrates that the expected annual downtime of seismically isolated buildings is less than that of the comparable non-isolated buildings regardless of the seismic isolation systems used. Among the cases of seismically isolated buildings studied in this paper, it is found that the most effective structural system to mitigate long downtime is the seismically isolated building with seismic isolators with enhanced sizes and with braced frames that are designed to be minimally compliant with the seismic design requirements of ASCE/SEI 7–16

Virtual Flight Demonstration of the Stratospheric Dual-Aircraft Platform

A baseline configuration for the dual-aircraft platform (DAP) concept is described and evaluated in a physics-based flight dynamics simulations for two month-long missions as a communications relay in the lower stratosphere above central Florida, within 150-miles of downtown Orlando.The DAP configuration features two large glider-like (130 ft wing span) unmanned aerial vehicles connected via a long adjustable cable (total extendible length of 3000 ft) which effectively sail without propulsion using available wind shear. Use of onboard LiDAR wind profilers to forecast wind distributions are found to be necessary to enable the platform to efficiently adjust flight conditions to remain sailing by finding sufficient wind shear across the platform. The aircraft derive power from solar cells, like a conventional solar aircraft, but also extract wind power using the propeller as a turbine when there is an excess of wind shear available.Month-long atmospheric profiles (at 3-5 min intervals) in the vicinity of 60,000-ft are derived from archived data measured by the 50-Mhz Doppler Radar Wind Profiler at Cape Canaveral and used in the DAP flight simulations. A cursory evaluation of these datasets show that sufficient wind shear for DAP sailing is persistent, suggesting that DAP could potentially sail over 90% of the month-long durations even when limited by modest ascent/descent rates.DAP's novel guidance software uses a non-linear constrained optimization technique to define waypoints such that sailing mode of flight is maintained where possible, and minimal thrust is required where sailing is not practical. A set of constraints are identified which result in waypoints that enable efficient flight (i.e., minimal use of propulsion) over the two month-long flight simulations. Waypoint solutions may need to be tabulated for a wide range of potential atmospheric conditions and stored onboard for quick retrieval on a real DAP.DAP's flight control software uses an unconventional mixture of spacecraft and aircraft control techniques. Flight simulations confirms that this controls approach enables the platform to consistently reach successive waypoints over the month-long flight simulations.The ability of DAP to transition between the sailing mode (i.e., cable tension is high) and standard formation flight (i.e., cable tension is low) is a vital capability (e.g., to enable intermittent turns while stationkeeping). A new method to perform these transitions has been identified and characterized with flight simulation which requires special aircraft modifications.The energy-usage of the DAP configuration during two month-long stationkeeping missions over central Florida (i.e., stationkeeping over Orlando) is evaluated and compared to that of a pure solar aircraft of the same weight and aerodynamic performance. DAP is shown to consistently reduce net propulsion usage while simultaneously increasing solar energy capture.A baseline 700 GHz communications system is described and its performance evaluated for the proposed mission over central Florida. It is found that the variable roll orientation of the aircraft would increase the power required to maintain coverage over the stationkeeping radius of 150 miles (e.g., by as much as 100% when DAP is 150 miles from Orlando), compared to level flight. This effect can be mitigated via additional antenna design complexity or a more restricted stationkeeping radius

In-vivo visualisation of the anatomical structures related to the acupuncture points Dai mai and Shen mai by MRI: A single-case pilot study

BACKGROUND: The concept of acupuncture point localisation in Traditional Chinese Medicine (TCM) is based on millenary practical experience. Modern imaging methods such as PET, MRI and SPECT have been used primary for the investigation of the mechanisms of action of acupuncture. In this pilot single-case study we have evaluated the technical possibilities for in-vivo imaging of the anatomical relations of acupuncture points using state of the art MRI. METHODS: Preliminary experiments relating to the quality of acupuncture needles under the setting of MRI were done both with stainless steel and gold needles. In a second step, in-vivo imaging was carried out. A licensed acupuncture practitioner (RM) chose two points belonging to the so-called extraordinary vessels. In 2 sequential, separate procedures, he inserted himself gold acupuncture needles using a neutral technique (known as Ping Bu Ping Xie) into the Dai mai and Shen mai points, i.e. gall bladder 26 and bladder 62. Imaging was done on a Siemens Magnetom Avanto MR scanner using a head array and body coil. Mainly T1-weighted imaging sequences, as routinely used for patient exams, were used to obtain multi-slice images. RESULTS: In the preliminary experiments only acupuncture needles made of gold showed enough stability in order to be used for further imaging procedures. Using an onion and a banana as an object, further studies showed that the gold needles produced a void defect that corresponds to the tip of the inserted needle, while at the same time an artefactually increased diameter was observed. The in-vivo experiments showed that the Dai mai point was in relation to the abdominal internal oblique muscle. The Shen mai point artefact showed up close to the longus and brevis peroneal tendons at the fibular malleolus. Side effects related to heating or burning were not observed. Improved anatomical recognition was obtained using 3D-volume rendering techniques. CONCLUSION: Through an adequate choice of acupuncture material (gold needles) as well as of ideal MRI imaging sequences it has been possible to visualize the anatomical characteristics at the acupuncture points Dai mai and Shen mai in-vivo. At the selected sites the needles showed a relation to tendino-fascial and muscular structures. These anatomical structures fit well into the recently described WOMED concept of lateral tension in which these acupuncture points play a regulatory role

Gangrena intestinal aguda masiva.

Acute mesenteric ischemia is a life-threatening vascular emergency that has a mortality rate between 70 and 80%. To improve the survival of these patients it requires a high indes of suspicion, early and aggresive resuscitation manuevers. Regardless of etiology, the acute interruption of perfusión of the small intestine and proximal colon progresses from potentially reversible physiologic alterations in tissue integrity to complete transmural infarction with hemorrhagic necrosisLa isquemia mesentérica aguda es una emergencia vascular que pone en peligro la vida y cuya mortalidad se encuentra en un rango de 70 a 80 %. Para mejorar la supervivencia de estos pacientes se requiere un alto índice de sospecha, maniobras tempranas y agresivas de resucitación. Cualquiera que sea su etiología, la interrupción aguda de la perfusión del intestino delgado y colon proximal progresa desde alteraciones fisiológicas potencialmente reversible en la integridad del tejido hasta el infarto transmural completo con necrosis hemorrágica