Finite Element Analysis and Long-Term Monitoring of a Highway Overpass Bridge with Newly Constructed Link Slabs and Modified Bearings

Joint failure, which causes leakage in bridge decks as well as deterioration in girders and substructures, is one of the most common concerns in highway bridges. Therefore, link slabs have been considered as a preventive maintenance method in eliminating these joints. This paper presents a pilot project that constructed the link slab system in Maryland, U.S., with modified bearings to improve its durability and reduce maintenance costs. Compared with the traditional bearing replacement design for the link slab systems, this project proposes a more economical method by removing the anchor bolts and restricting sliding plates of the fixed bearings at both abutments to match the designed boundary conditions while avoiding the high cost of jacking girders and replacing bearings. Furthermore, numerical analysis and structural health monitoring were conducted and validated to investigate the effectiveness of the link slab design with various high performance concrete materials. After the one-year monitoring period, the link slab system is verified to be in fully functional condition and the bearing modification design is verified to be effective.

PROFITABLE WASTE OIL BURNINGSYSTEM

By autonomously navigating the water's surface, Sea swarm proposes a new system for ocean-skimming andoil removal. Sea swarm uses a photovoltaic-powered conveyor belt made of a thin nanowire mesh to propel itself and collect oil. The nanomaterial, patented at MIT, can absorb up to 20 timesits weightin oil. The flexible conveyor beltsoftly rolls over the ocean'ssurface, absorbing oil while deflecting water because of its hydrophobic properties Sea swarm is meant to figure as a fleet, or “swarm” of vehicles, which communicate their location through GPS and Wi-Fi so as to make an organized system for collection that can work continuously without human support. Sea swarm works by detecting the sting of a spill and moving inward until it's removed the oilfromone site before joining other vehicles that are still cleaning. The fleet uses cuttingedge nanotechnology to unravel current environmental problems while envisioning long-term solutions for the longer term. With a replacement design strategy, we will revive and preserve the standard of our oceans.

Clinical Radiographical Outcomes and Complications after a Brand-New Total Ankle Replacement Design through an Anterior Approach: A Retrospective at a Short-Term Follow Up

Recently, the progress in techniques and in projecting new prosthetic designs has allowed increasing indications for total ankle replacement (TAR) as treatment for ankle osteoarthritis. This retrospective work comprehended 39 subjects aged between 47 and 79 years old. The patients, observed for at least 12 months (mean follow up of 18.2 ± 4.1 months), have been evaluated according to clinical and radiological parameters, both pre- and post-operatively. The AOFAS and VAS score significantly improved, respectively, from 46.2 ± 4.8 to 93.9 ± 4.1 and from 7.1 ± 1.1 to 0.7 ± 0.5 (p value < 0.05). At the final evaluation, the mean plantarflexion passed from 12.2° ± 2.3° to 18.1° ± 2.4° (p value < 0.05) and dorsiflexion from a pre-operative mean value of 8.7° ± 4.1° to 21.7° ± 5.4° post-operatively (p value < 0.05). This study found that this new total ankle replacement design is a safe and effective procedure for patients effected by end-stage ankle osteoarthritis. Improvements have been demonstrated in terms of range of motion, radiographic parameters and patient-reported outcomes. However, further studies are needed to assess the long-term performance of these prostheses.

Grain Yield Stability of Cereal-Legume Intercrops Is Greater Than Sole Crops in More Productive Conditions

The intercropping of two or more crop species on the same piece of land at a given time has been hypothesized to enhance crop yield stability. To address this hypothesis, we assessed the grain yield stability of various barley-pea and wheat-faba bean mixtures grown in seven experimental field trials (locations) across Europe during two years with contrasting weather (2017 and 2018). Three different yield stability measures were used, all based on the expected yield variability of the mixture components grown as sole crops, and the corresponding observed yield variability of the same components grown in 50:50 mixtures in a replacement design. Stability indices were calculated as ratios between the expected and observed variabilities, with values > 1 indicating greater stability of the intercrops. Mean grain yields tended to be higher in intercrops than sole crops. However, in contrast to our hypothesis, the observed (intercrop) yield stability was similar or lower than the expected (sole crop) stability in most locations except one. Furthermore, yield stability significantly increased with increasing mean yields when assessed across differentially productive locations. The results are relevant for the designing of intercropping systems as a means to increase yield stability and the resilience of cropping systems.

Replacement of Cable Stays in Yonghe Bridge in Tianjin, China

Cable replacement is one of the most important approaches for retrofitting an existing cable-stayed bridge. The Yonghe Bridge opened to traffic in 1987 and was the largest concrete cable-stayed bridge in Asia at the time. After nearly 20 years in service, its stay-cable system was completely replaced. The present paper details the key technical points of cable replacement in this bridge, including causes of replacement, cable replacement design, construction monitoring during replacement, and cable tension tuning after replacement. Based on the measurements during construction, the variation in structural condition indexes was thoroughly investigated, such as cable forces throughout the bridge, geometry profile of bridge deck, and tower horizontal displacements. The structural changes due to cable replacement were evaluated, and then, a relatively desirable scheme of cable adjustment was correspondingly put forward. The measured results showed that, influenced by the accumulated tolerances of cable forces during construction, cable replacement may often lead to a further deviation of structural condition. In this instance, cable adjustment is an effective compensation measure to improve the overall structural condition of the bridge. The practice of cable replacement in the Yonghe Bridge has provided some valuable experience or beneficial references for the similar retrofitting cases.