Purpose -This paper sets out to look at the different types of crawl spaces that are found in Sweden and why they are still being used in today's constructions despite the advice of building experts to avoid their use. Design/methodology/approach -Literature reviews were performed to look at the types of crawl space foundations available as well as the advantages and disadvantages of each type and to look at the economic costs associated with repairing a damaged home that could be attributed to a crawl space foundation. Interviews were conducted with engineers with regard to moisture design issues in the Swedish building industry. Findings -This study shows that there are five traditional types of crawl spaces used in Sweden: plinth, outdoor ventilated, indoor ventilated, unventilated, and suspended crawl space foundations, four of which are currently available to builders. Despite all of the available knowledge regarding the disadvantages and the past performance of the outdoor ventilated crawl spaces, companies in Sweden are still using this design and are still experiencing expensive problems. Research limitations/implications -This paper is limited to Sweden. The situation in other countries was not specifically examined; however, it appears that other countries are also facing the same problems and this paper may provide some insight into why. Originality/value -This study shows that there are many ways to construct a crawl space, some of which are considerably less risky than others. The study also indicates that the building industry in general seems to lack the theoretical background or incentive to utilize these variations properly or completely move away from these designs.
A system for actively changing the stiffness of a long, thin, flexible robotic manipulator has been designed for cardiologists to use in a range of diagnosis and treatment procedures. Low-stiffness manipulators, such as catheters, are ideal for steering through vasculature with low risk of tissue injury. However, such instruments are not well-suited for applying force to tissue. The proposed system solves this problem by using a series of bead-shaped vertebrae containing pull wires to actively change the stiffness of the catheter, similar to gooseneck surgical retractors. Individual wires steer the catheter to a desired location. All wires are then tensioned to create friction between each vertebra and prevent sliding, therefore resisting motion. While this design concept has been implemented manually in various settings for decades, fine robotic control of the friction and stiffness of the system relies on a thorough understanding of the friction properties between vertebral segments. We have developed an analytical model to understand the interactions between vertebrae and determine the relationships between system parameters and the overall stiffness of the catheter. Experiments validated the calculations from the model and the functionality of the system by applying known loads to the tip of the catheter and measuring the catheter displacement. The catheter stiffness was measured to range from 100 N/m to 800 N/m, which is sufficient for performing many surgical tasks on tissue. This system can be useful in minimally invasive procedures involving direct instrument contact with tissue by improving accuracy, safety, and work flow.
The hot water circulation system in a building is a system which helps prevent Legionella problems whilst ensuring that tenants have access to hot water quickly. Poorly designed or implemented systems not only increase the risk to people’s health and thermal comfort, but even result in an increase in the energy needed for this system to function properly. Results from previous studies showed that the total hot water circulation system loss can be as high as 25 kWh/m2 heated floor area per year. The purpose of this project is to measure the total energy use per year of the hot water circulation system in about 200 multifamily dwellings of different ages to verify that a system loss of 4 kWh/m2, year is a realistic assumption for both newer and older/retrofitted buildings. The preliminary results from the first 134 measurements showed that the assumption of 4 kWh/m2, year is rarely fulfilled. An average energy use of more than three times this is more common, even in newer buildings. Whilst some of the total energy lost is used to heat the buildings, it is not desirable because it is an uncontrolled energy flow.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.