A DESIGN OF AN EXPERIMENTAL SYSTEM FOR TRAPPING PRESSURE OF AGRICULTURAL GEAR PUMP

Abstract: The trapping phenomenon stems from the principle of gear pumps, and it affects directly the performance and life of gear pump. Reducing pressure in trapping area is an important aspect to improve working performance of gear pump, and how to test the pressure of trapping area is one of the most important problems. According to such requirements, an experimental system has been designed, and then relevant experiments are conducted on the designed experimental system. The experimental results indicate that the system can fulfill the requirements commendably

A Lightweight Universal Gripper with Low Activation Force for Aerial Grasping

Soft robotic grippers have numerous advantages that address challenges in dynamic aerial grasping. Typical multi-fingered soft grippers recently showcased for aerial grasping are highly dependent on the direction of the target object for successful grasping. This study pushes the boundaries of dynamic aerial grasping by developing an omnidirectional system for autonomous aerial manipulation. In particular, the paper investigates the design, fabrication, and experimental verification of a novel, highly integrated, modular, sensor-rich, universal jamming gripper specifically designed for aerial applications. Leveraging recent developments in particle jamming and soft granular materials, the presented gripper produces a substantial holding force while being very lightweight, energy-efficient and only requiring a low activation force. We show that the holding force can be improved by up to 50% by adding an additive to the membrane's silicone mixture. The experiments show that our lightweight gripper can develop up to 15N of holding force with an activation force as low as 2.5N, even without geometric interlocking. Finally, a pick and release task is performed under real-world conditions by mounting the gripper onto a multi-copter. The developed aerial grasping system features many useful properties, such as resilience and robustness to collisions and the inherent passive compliance which decouples the UAV from the environment.Comment: 21 pages, 19 figures; corrected affiliation

Articles indexats publicats per investigadors del Campus de Terrassa: 2017

Aquest informe recull els 241 treballs publicats per 222 investigadors/es del Campus de Terrassa en revistes indexades al Journal Citation Report durant el 2017Postprint (published version

Sub-lunar Tap Yielding eXplorer (STYX) & Surface Telemetry Operations and Next-generation Excavation System (STONES)

The NASA RASC-AL Moon to Mars competition challenges student teams to develop a lightweight, durable, and hands-off method for extracting water from Martian/lunar subsurface ice layers while mapping soil density profiles. Future interplanetary expeditions are dependent on the availability of clean water and this project aims to accomplish this task. The challenge description enumerates several criteria to be met for successful designs. For further information, the STYX & STONES team conducted research on Cal Poly’s competition project from last year to consider the areas for redesign. As such, the team has utilized the background research from relevant patents and journal articles to consider brainstorming potentially viable solutions. Based on these solutions for each subsystem, the team converged the ideas using a series of decision matrices into a final design direction. In addition to reviewing the STYX design, several new considerations were made for the scope of this project. Primarily, this year’s team focused on developing a prototype that has the capability of operating in an extraterrestrial environment and thoroughly fulfilling the requirements posed by NASA. To visualize the requirements, the team created a list of customer needs, a House of Quality diagram, and an engineering specifications table. Additionally, the STYX & STONES team discussed the design process it plans to follow including major project milestones. Specifically, the team plans to excel in collecting more than five quarts of water autonomously while successfully identifying the overburden layers – tasks that previous teams have struggled with. The team’s design direction includes two main components: a masonry drill bit and an auger- heater probe hybrid tool. The masonry drill bit will create a hole in the overburden using the force from a rotary hammer. The heater probe tool will then be moved to align with the hole and be driven into the loosened overburden using the force of a small gear motor. The heater probe will then melt ice using a hot waterjet and deliver water via a peristaltic pump and a two-stage filtration system. To verify the design, the team completed a multitude of analyses and tests for each subsystem and the prototype as a whole. Through drilling tests, the team found that the rotary hammer and masonry bit can easily cut through all overburden layers while keeping weight on bit (WOB) below 150N. Similarly, the load cells attached to the drill carriage were tested and proven to be accurate at recording WOB data and providing feedback to the controller to monitor WOB. Furthermore, the load cells proved successful at recording accurate WOB data that can be analyzed to determine overburden composition. The pumping system was also tested and was capable of effectively moving water through all filters and delivering fluid to the waterjet. More tests were completed to verify the heater probe tool; these tests included controlling heater temperature, melting ice, expelling water through the waterjet, and removing loose material from the hole. To verify the design requirements, the team has completed analysis pertaining to each subsystem including the drill, heater probe, frame, and control systems. The team is confident in the drilling design based on testing and vibrations analysis. In the same manner, the team verified that the 12V peristaltic pump will have enough pressure head rise based on analysis and prototype testing. Using the prototype heater probe as a reference, the team fully characterized the heat transfer parameters of the final design and is confident the auger will be effective considering surrounding debris. Finally, the team tested the water jet design using 120oF water which provided optimistic results that the water jet will significantly expand the melt radius per hole. As a next step, the team will be testing the mechanical and controls systems simultaneously using manufactured parts. The following report details the subsystems and relevant information

Efficacy and Feasibility of Alginate Bait for the Louisiana Commercial Blue Crab (Callinectes sapidus) Fishery

Louisiana leads all U.S. states in blue crab (Callinectes sapidus) landings, but high fuel and bait costs have hindered commercial fishing productivity of Louisiana in recent years. The primary baitfish, Atlantic menhaden (Brevoortia tyrannus), has steadily increased in price and decreased in availability, while crab prices remain low. To reduce costs for fishermen, an alternative bait was developed that incorporates shrimp waste into a semi-rigid alginate matrix. Lab testing and preliminary field tests show that shrimp-alginate bait may be a suitable alternative to menhaden for Louisiana crab fishermen. I evaluated bait performance by conducting field sampling to compare catch rates and longevity of standard baitfish and shrimp-alginate bait. I performed seasonal fishery-independent testing at three sites across Southern Louisiana from summer 2014 to spring 2015, and tested the bait on commercial crabbing boats throughout coastal Louisiana during peak crab season in 2015. Catch rates of shrimp-alginate were less than menhaden overall, however, bait performance changed with site and season, and did not significantly differ when I evaluated commercially relevant crab classes. Analysis of remaining bait quantity after fishing showed that shrimp-alginate remains intact as long, or longer, than standard baitfish during peak crab fishing from June through August. After testing shrimp-alginate bait in the field, I evaluated the economic feasibility of producing the bait with a partial budget supply line. With its current formulation, shrimp-alginate can only be produced at a cost lower than menhaden (currently $0.50/lb.) under optimal production scenarios, however, slight modifications that improve shelf life could dramatically decrease the cost of bait production. Findings from both field work and feasibility analysis show promise in the alternative shrimp-alginate bait with given improvements to catch rate efficacy and product storage

Integrated Guidance for Tidal Shorelines

Tidal shorelines are the site of complex interactions between terrestrial and aquatic systems. These areas have values that far outweigh their relative size in the larger ecosystem. They are exceptionally important habitat for a wide variety of organisms, some living primarily on land, others that live in water, and a few that are found only in the intertidal zone between land and water. Tidal shoreline systems provide important filtration capacity for materials carried in runoff and groundwater. They are uniquely valued by human users of coastal systems. In Virginia, tidal shoreline systems are managed in small segments, rather than as a whole unit. Local governments implementing the Chesapeake Bay Preservation Act manage the riparian zone, intertidal areas fall under the purview of local wetland boards, and the subaqueous environment is the responsibility of the Virginia Marine Resources Commission. Each of these programs tends to seek avoidance of impacts in areas under their jurisdiction. This preference for the status quo can be in conflict with shoreline management that optimizes the tradeoffs in public and private benefits. Recognition that particular shoreline management options may not be uniformly desirable from different regulatory perspectives means coordination among management agencies will be essential. The basis for coordination is logically the rationale for establishment of the various regulatory programs – sustaining public benefits from environmental services. The desire to maintain the capacity of the natural system to do things that are important and valuable to the general citizenry of the Commonwealth underpins the riparian, intertidal and subaqueous lands management programs operating in Virginia. These programs uniformly seek to accommodate private development interests within the broader goal of sustaining ecological services. There are currently a variety of guidelines developed by local and state programs managing shoreline development activities. These include the Virginia Marine Resources Commission guidelines for tidal wetlands, subaqueous lands and coastal primary sand dunes. In addition, the Department of Conservation and Recreation’s Chesapeake Bay Local Assistance Division and Shoreline Erosion Advisory Service have both issued guidelines for riparian land management. There are, however, no comprehensive guidelines that synthesize the objectives of all these programs. It has become increasingly apparent that in order to reduce the cumulative and secondary impacts of activities within the multiple jurisdictions and multiple management programs affecting the littoral and riparian zones, better coordination and integration of policies and practices is necessary. It may be possible to address the gap of the jurisdictional limitations of the various programs that manage the shoreline by providing enhanced technical guidance to promote integrated management decision-making

Application of Semi-Hydrophobic Layers to Decrease Bare Soil Evaporation

Evaporative water loss from bare agricultural soils is a primary area of water conservation research. Mulching is the commonly utilized method to decrease evaporative water loss. The most commonly utilized mulch is nonbiodegradable polyethylene sheeting because it tends to decrease evaporative water loss and increase crop yields more than environmentally friendly mulches. This study aimed to test the utility of sand coated with polymerized soybean oil (i.e., hydrophobic sand) as a treatment to reduce bare soil evaporation and an alternative to current practices. Evaporation rates were measured in laboratory soil columns containing both treated and untreated soils. Treatment parameters were varied systematically (i.e., ~1 cm and ~2 cm layer thicknesses, medium and coarse grain sizes of treated soil). Treated soil was Water Drop Penetration Time (WDPT) tested before and after degradation testing, and physical properties of the treated soil including hydraulic conductivity and porosity were also measured. Pre degradation WDPT tests showed that the polymerized soybean oil slightly hydrophobized the sands, and the treated sands significantly decreased evaporative water loss (\u3e90%) prior to the bare soil’s Stage 2 evaporation. Furthermore, the coarser hydrophobized sands were minorly less effective at decreasing evaporation as the medium grain hydrophobic sands, but the coarser grains had a WDPT of less than ~3 seconds (less after wetting) and could therefore theoretically allow for water infiltration