To describe the physical principles of the vortex effect to better understand its applicability in minimally invasive percutaneous nephrolithotomy (MIP) procedures.
Two acrylic phantom models were ...built based on the cross-sectional area (CSA) ratio of a MIP nephroscope and access sheaths (15/16F and 21/22F MIP-M™, Karl Storz®). The nephroscope phantom was 10mm in diameter. The access sheaths had diameters of 14mm (CSA ratio: 0.69) and 20mm (CSA ratio: 0.30). The models were adapted to generate hydrolysis, and hydrogen bubbles enhanced flow visualization on a green laser background. After calibration, the experimental flow rate was set to 12.0mL/s. Three 30-second trials assessing the flow were performed with each model. Computational fluid dynamic simulations were completed to determine the speed and pressure profiles.
In both models, as the incoming fluid from the nephroscope phantom attempted to move toward the collecting system, a stagnation point (SP) was demonstrated. No fluid entered the collecting system phantom. Utilizing the 14mm-sheath, we observed a random generation of several vortices and a pressure gradient (PG) of 114.4N/m2 between the nephroscope’s tip and SP. In contrast, examining the 20mm-sheath revealed a significantly smaller PG (19.4N/m2) and no noticeable vortices were noted.
The speed of the fluid and equipment geometry regulate the PG and the vortices field, which are responsible for the production of the vortex effect. Considering the same flow rate, a higher ratio between the CSA of the nephroscope and access sheath results in improved efficacy of the vortex effect.
This paper discusses systematic efficiency considering the efficiency of both a motor and airflow in an inverter-driven single-phase brushless direct-current (BLDC) motor with two different ...lamination designs for a cordless vacuum cleaner. In other words, multi-physical lamination design has to be conducted, and hence, the shape and placement of a whole electromagnetic structure are investigated in terms of a tradeoff between the electrical and mechanical efficiencies. In this paper, a single-phase BLDC motor for cordless vacuum cleaners is designed to satisfy starting and continuous torques by means of asymmetric air gap, and fluid analysis is performed to determine which shape of a single-phase BLDC motor has better system efficiency. The prototype of a single-phase BLDC motor has been tested, and the speed of the operation is ranged from 84468 r/min up to the rated speed of 100020 r/min. The motor efficiency of 94.7% has been measured to verify a good match with the estimated efficiency of 94.5%.
Cleaning houses is very difficult for people in terms of time and labor. The fact that vacuum cleaners are wired and slow is not advantageous in terms of ease of use. For this reason, many robot ...vacuum cleaners that can replace traditional vacuum cleaners have started to appear on the market. In our project, we aimed to design and simulate a smart vacuum cleaner. The smart vacuum cleaner will work with a map by detecting the environment and obstacles around it.
Upright vacuum cleaners for home use have been replaced with lightweight cordless stick vacuum cleaners, specifically those with the center of mass (CoM) near the handle. The current study evaluated ...upper extremity muscular loads associated with household floor vacuuming with the high CoM stick vacuum cleaners. Twenty participants conducted vacuuming on tiled and carpeted floors with straight and curved back-and-forth motions using medium (2.92 kg) and heavier weight (3.56 kg) cordless stick vacuums. The myoelectric signals of their upper extremity muscles were quantified during vacuuming. Mean normalized activity ranged from 8.2% to 20.2% of the maximum contraction capacity, with greater activity when vacuuming carpeted floors with a heavier vacuum cleaner. Study findings indicate that floor vacuuming with a cordless stick vacuum may not be as ergonomically efficient as assumed by their lighter weight. Instead, it is a physically demanding housekeeping activity that needs ergonomic attention.
•Muscular loads were assessed during floor vacuuming with cordless stick vacuums.•Stick vacuums demanded 8.2%–20.2% of contraction capacity of upper limb muscles.•Users hold about 70% of weight due to the high center-of-mass of stick vacuums.•Vacuuming with stick vacuums could be more difficult than heavier upright vacuums.
In 1937, the Swedish palynologist Gunnar Erdtman (1897–1973) mounted two adapted vacuum cleaners atop an ocean-going liner and set out to obtain air samples as he crossed the Atlantic Ocean. The ...devices were able to capture samples of airborne pollen which were related to air volume and distance from land. The results of this investigation are still cited in the scientific literature, but a study of publications demonstrates that the ocean study had land-based antecedents. Furthermore, archival investigation reveals the background to such studies, including the technical plans for Erdtman's ‘aerosol collector’, records of raw data from the voyage, draft portions of the key publication, photographs and the precise location of the land-based equipment. A storage loft in the Swedish Museum of Natural History in Stockholm has been found to house a surviving aerosol collector.
Low-power and high-speed BLDC(Brushless DC) motor is widely used in vacuum cleaners. This paper presents a sensorless speed control scheme for a high-speed BLDC motor of a hand-stick vacuum cleaner ...using a variable slope sliding mode observer(SMO). The SMO using the signum function is very effective for the sensorless estimation of the BLDC motor. However, the chattering effect on the slide surface from the signum function decreases the sensorless performance in the wide speed range. The sigmoid function instead of the signum function can reduce the chattering effect. However, the convergence is inversely proportional to the reduced chattering effect. In order to reduce the chattering effect and keep the proper convergence performance, the proposed method uses a variable acceleration slope of the sigmoid function. In the low-speed range, the acceleration slope of SMO is decreased to reduce the chattering. And, it is increased to improve the convergence in the high-speed region. The acceleration slope of the sigmoid function is designed as a function of the estimated speed to keep the constant convergence with reduced chattering in the sensorless speed and position estimation. In order to verify the proposed sensorless control scheme, 115 krpm speed 540W BLDC motor for a vacuum cleaner is tested with various SMO methods. In the experimental results, the proposed method shows better sensorless speed control performance in the wide speed range.
Designers and engineers need better tools and methods to create highly repairable products. Design for disassembly and reassembly is an important product related design feature that can enhance ...repair. In a highly repairable product, the components that fail most often should be easily accessible for repair or replacement. This paper describes the development of a method to visually map the disassembly of a product, showing different routes towards target components. These components can be those with a high potential failure rate (important for repair), embodied environmental impact (important for recycling) and economic value (relevant for component harvesting), depending on the circular strategy under consideration. The ‘Disassembly Map’ method is set up to guide product design and is aligned with the most recent research and standards on product repairability. The ease of disassembly is assessed on Four main design parameters are considered in this method to assess the ease of disassembly of: disassembly sequence/depth, type of tools, fastener reusability/reversibility, and disassembly time. In contrast to most of the related literature found, the Disassembly Map method is not based on the use of an algorithm for the automatic calculation of optimised disassembly sequences. It asks designers and engineers to analyse each disassembly step using standardized visual elements based on the ease of Disassembly Metric (eDiM) and the Maynard Operation Sequence Technique (MOST). Insights gathered from this analysis and the resulting visualisation can be used in an iterative product development process. The method was developed by analysing seven vacuum cleaners. Its effectiveness was then tested by redesigning one of them, enhancing its repairability.
•Mapping product architecture is essential to identify design features hindering repairability.•The Disassembly Map is a simple and intuitive method for Design for Repair, based on product architecture mapping.•To create better repairable products, designers should consider design for disassembly in early design stages.•A key product related design feature to improve repairability is optimising target component accessibility.•Different types of disassembly interdependences between components can impact design for disassembly.
Employed for the first time in 1986, DNA profiling is nowadays established as one of the most widely used forensic techniques worldwide. However, until today, no efficient sampling technique existed ...to collect DNA from human skin cells from a large area, not to say from the floor of an entire room. This has been extremely unfortunate, as there is enormous forensic potential in these DNA traces from the ground to provide clues as to who has been present at a particular location, i.e. at the crime scene. By desquamation, humans loose several millions of skin cells per day, everywhere they stand, sit or walk; and they can do little about it. We developed a fast and simple method by which we can make use of all those lost skin cells. We use a vacuum cleaner equipped with a specialized filter cartridge to sample the ground. Fragmentation of the filter membrane and subsequent parallel processing of the filter fragments, using a modified Chelex® 100 extraction protocol, significantly reduce the complexity of the dust mixture. In this way, a large number of interpretable major contributor DNA profiles can be generated from individuals who have been present on the sampled surface. Overall, at least 38 % of the generated DNA profiles from all sampled test areas fulfilled the criteria for submission of single major contributor profiles to the Swiss DNA database. As demonstrated through a mock crime scene scenario simulating an indoor stabbing event, the perpetrator's DNA could be found on the floor even after a very short stay in the room of less than one minute. Furthermore, already the first application of the method at a real crime scene led to relevant case information for the police. Given its large investigative potential, we recommend Total Human DNA Sampling as a helpful complemental forensic tool to conventional DNA trace collection in major crimes.
•First DNA sampling method for large areas.•High percentage of database suitable DNA profiles through subsampling.•DNA profiles correspond with the presence of individuals on the sampled areas.•Detection of suspect DNA is possible after a very short stay in the room.•Total Human DNA Sampling recommended as standard for major crimes.
This paper describes the design of a single-phase high-speed flux reversal motor (FRM) for use in a domestic application (vacuum cleaner). This machine has a simple and reliable rotor structure, ...which is a significant advantage for high-speed applications. An FRM design in which the inner stator surface is entirely used allows it to decrease its volume and increase its efficiency. The mathematical modeling, based on the finite element method, and the optimal design of the high-speed single-phase FRM are described. The criterion of optimization and the selection of a proper optimization algorithm are discussed. Since the finite element method introduces a small but quasi-random error due to round-off accumulation and choosing the mesh, etc., the Nelder-Mead method, not requiring the derivatives calculation, was chosen for the optimization. The target parameter of the optimization is built for the motor efficiency when operating at different loads. Calculations show that the presented approach provides increasing motor efficiency during the optimization, particularly at underload.
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