Types Of Seals Research Articles

HOSPITAL ACCREDITATION IN THE BRAZILIAN CONTEXT

Introduction: Hospital accreditation aims to promote patient care and assistance and quality in the institution's sectors, aiming at process safety, integrated management and continuous improvement. Objective: to identify in Brazil in 2021 the types of establishments certified in the country, as well as their respective states, type of management and certification seals in force in the national territory. Method: Descriptive and retrospective study with a quantitative approach. The search was carried out on the website of the National Accreditation Organization in October 2021. Variables of interest were considered: types of accredited health establishments, types of certifications in force in the national territory, type of management of the accredited establishment, state and city of establishments. Results: The analyzes identified that in the month of October 2021 there are 906 certifications in the Brazilian territory. Of these, 760 (84%) of the accreditations in the national territory are private institutions and 337 (37.2%) are hospital institutions. As for the certification seal, 201 (22.1%) of the institutions are accredited (level I) and 341 (37.6%) are located in the state of São Paulo. Conclusions: It was possible to obtain a view of the accreditation certifications in force in Brazil through their characterization, in order to visualize which types of seals, establishments and states are covered with health establishments committed to quality and excellence in care.

Macro- and Mesoscopic Design for Cabin Door Pretightened Fabric Rubber Seal Structure

The aviation fabric reinforced rubber seal structure is the key component of aircraft cabin seal and load transfer mechanism, and its performance directly determines the safety and reliability of high-performance aircraft. The inner and surface fabric rubber layers of the cladding are characterized by a macroscopic nonorthogonal anisotropic constitutive model and a representative volume element based on mesostructure, respectively. Compared with the conventional single/ring belt seal, this novel cladding/core type of seal involves the strong anisotropy; the pretightened assembly process; and the interaction of cladding/core, cladding/fixture, and core/fixture. The effectiveness of the macro- and mesoscopic analysis method is verified by experiments and numerical simulation. In addition, the effects of friction coefficients, pretightened displacement, and material orientations on the mechanical behaviors of the seal are also investigated. To our knowledge, this is the first systematic study on the cladding/core type of seal structures, and our results provide a valuable reference for the evaluation and optimization of aircraft seal in henceforth research.

Rotary Shaft Seals: Correlation of Wear Formation at the Sealing Edge and Shaft under Various Operating Conditions

Elastomeric rotary shaft seals are a common seal type for various industrial applications. They are comparably cheap and easy to use and offer an overall good performance. But the wear behavior of these sealing systems is not fully understood and not predictable so far. If a lip seal fails, it causes high maintenance costs and environmental damage. In this article, various tribological conditions are considered. For this purpose, the sealing systems are tested with multiple operating conditions relevant to practice. Three test series are conducted with rotary shaft seals BAUM5X7 75FKM585 on plunge ground shafts. The tests are carried out with two different circumferential velocities of the shaft (4.2 and 10 m/s), three different oil sump temperatures (40, 80, and 120 °C), two different lubricant types (FVA 3 and PG 3), and five different test durations (between 100 and 625 h). For a complete acquisition of the system condition, all shaft surfaces are measured in 2D and 3D before and after the test runs and the wear of the sealing edges is evaluated with a recently developed laser line triangulation method on the complete circumference of the sealing rings. Results show large amounts of wear, depending significantly on the operating conditions. A strong correlation of the wear effects in the tribocontact area of the sealing system becomes evident. This article helps to understand and avoid critical operating conditions concerning abrasive wear.

Numerical Investigations on Static and Rotordynamic Characteristics for Two Types of Liquid Hole-Pattern Seals With Tilted Cavities

Abstract Two types of liquid hole-pattern seals with axially oblique (A-HPS) or circumferentially oblique (C-HPS) hole cavities are designed. To evaluate the leakage and rotordynamic characteristics of the liquid hole-pattern seals, a 3D transient perturbation method is employed, which based on the multifrequency one-dimensional rotor whirling model and the mesh deformation technique. The accuracy and reliability of the proposed numerical approach is demonstrated based on the published experimental data of the leakage and rotordynamic force coefficients for a hole-pattern seal (HPS). Seal leakage and force coefficients are presented and compared for the A-HPS (axially oblique angle α=−30degto30deg), C-HPS (circumferentially oblique angle β=−30degto30deg), and HPS (α = 0, β = 0) at various rotational speeds (n = 0.05, 2.0, 4.0, and 6.0 krpm). Results reveal that the tilted hole cavity with positive α or β can reduce the seal effective clearance and strengthen the kinetic dissipation in hole cavities, yielding less leakage by 5–10%, especially at higher rotational speeds. The tilted hole cavity with a positive oblique angle (α=30deg,β=30deg) results in a moderate growth (by ∼6% for the A-HPS, by ∼15% for C-HPS) in the effective stiffness. Furthermore, the tilted hole cavity shows a very weak influence (<4.0%) on the effective damping, particularly for higher rotational speeds and vibration frequencies. Considering the decreasing leakage and nonworse rotordynamic characteristics, a tilted hole cavity with suitable positive oblique angles (10deg–30deg) is beneficial for the liquid hole-pattern seal.

Stamp Seals in and out of Georgia

The Article discusses the Late Bronze-Early Iron Age clay seals, mostly stamps which have been discovered on the territory of Georgia and also their analogues. I have started to investigate this issue on my master and on that stage of study I had done catalogue, classification and the research of the given materials. As a PhD dissertation I am planning to finish the study of the Late Bronze-Early Iron Age Georgian Clay seals.As it is seen from the study of the Late Bronze-Early Iron Age Georgian seals in most cases their surface depicts the ornamental motives which were very spread in the other ancient cultures in different periods, but at the same time some of the depictions are local. As it is known societies which had been living on the territory of Georgia had intercultural and trade relations with different cultures, such as Anatolian, Aegean, and Mediterranean, near Eastern and so on. And these relations could be seen on different materials discovered during the archaeological excavations. As I have already mentioned Georgian seals depictions have parallels in different ancient cultures from Europe to Indus valley. Before appearing in Georgia stamp seals had been spread in some other ancient cultures earlier. Probably this type of seals had been entered on the territory of Georgia from these cultures. One of the main goals of my works is to find out from which culture, with which way and when it started to distribute stamp seals on the territory of Georgia. to research this issue, I use some methods. For example: I compare Georgian seals with its analogues and also, I mark the discovery places of its analogues on the map chronologically. This will help me to define the distribution territories of this kind of the seals and its spreading routs, moreover, I will be able to see from which territory were distributed stamp seals on the territory of Georgia. It is true that the seals played a very important role in this period people’s everyday life because they have been found at almost all Georgian significant archaeological sites. unfortunately, there exists many vague facts about Late Bronze-Early Iron Age Georgian archaeology. So, studying this kind of important materials will clear up some of the undefined issues about this period Georgia too. the fact that Georgian seals finds many analogues among the ancient worlds seals grows this artifacts importance, and it is evident that Georgian seals must be studied among the other cultures’ seals.

Flow analysis of the hole diaphragm labyrinth seal by the CFD method

The computational fluid dynamics (CFD) method is an efficient way to reduce the obstacles in fluid studies. Good use of the CFD method on the seal-rotor system area was proven again in this paper. The flow analyses of a new type of annular seal, the hole diaphragm labyrinth seal (HDLS), were studied by Fluent. Complex working conditions were considered to further understand the flow field variation trend. The results show that the maximum velocity component was obtained in the middle cavities perpendicular to the whirl direction. The velocity distributions before the first cavity and behind the last cavity show a different trend under a 50 Hz whirl frequency than that of other whirl frequencies, which can be described by the most apparent throttling effect of the first blade and the diffuse effect behind the last blade. It is helpful to further understand different annular seal characteristics by detailed fluid information analyses.

Geometry, formation mechanisms, and hydrocarbon exploration significance of Pishan Caldera, Tarim Basin, northwest China

The discovery of an oil reservoir in Pishan Caldera of the Tarim Basin, northwest China, highlights the hydrocarbon exploration potential of large calderas. We used 3 D seismic interpretations, waveform clustering analysis, and seismic profiles to investigate the origin and evolution of Pishan Caldera, along with the mechanisms of hydrocarbon accumulation, and its significance for future oil and gas exploration. Pishan Caldera is located at depths of >7000 m, has an elliptical shape, extends over an area of 25 × 20 km, and is surrounded by ring faults. Pishan Caldera were the result of magma withdrawal and later magma intrusion. Volcanic eruptions, caldera collapse, and reactivation of Pishan Caldera resulted in Cretaceous oil migration and accumulation in Cretaceous breccia reservoirs. Ring faults, dense fracture networks, and lava tubes associated with the caldera acted as conduits for upward hydrocarbon migration. We propose a generalized model for hydrocarbon reservoirs related to the caldera, which includes five major reservoir types: drape anticline, fault block, volcanic-trapped, laterally sealed and lava tube type. Further efforts should be made to identify deep caldera structures that may be targets for hydrocarbon exploration.

The evaluation of the usefulness of CO2 laser in microsurgical resection of brain tumors.

Background: Since its introduction to surgery, the CO2 laser has been used in the treatment of various neurosurgical pathologies as it combines cutting, vaporizing, and coagulating properties in one tool and has a safe penetration depth. In this case series of 29 patients, we present the evaluation of the usefulness of the closed system type – sealed tube surgical CO2 laser in the surgical removal of brain tumors.Methods: The Sharplan 40C model SurgiTouch, sealed tube type CO2 laser, was used in the resection of 29 brain tumors; 13 meningiomas, six metastases, nine gliomas, and one acoustic neuroma. The same senior surgeon (BT) assessed and classified the benefit provided by the CO2 laser in the resection of the neoplasms to considerable (Group 1), moderate (Group 2), and poor (Group 3).Results: Group 1 included 14 patients with 13 meningiomas and one acoustic neuroma, Group 2 included six patients, all of whom had metastases, and Group 3 included nine patients of which six had glioblastoma and three astrocytoma. No complications or technical problems occurred due to the use of the CO2 laser.Conclusion: The CO2 laser is a valuable complementary tool in brain tumor surgery displaying high efficacy and practicality in the resection of neoplasms which are fibrous and have hard consistency. It has high acquisition and maintenance cost and cannot replace the bipolar diathermy. The newest generation of flexible CO2 laser fiber provides more ergonomy and promises new perspectives of its neurosurgical use in the modern era.

Static Characteristics of Finger Seal considering Contact between Fingers and Rotor

Finger seals are a new type of seal with good sealing performance and long service life. The noncontacting feature relies on the gas film force. However, when the seal works in an unsuitable environment or its design parameters are not reasonable, the lifting pad may not be able to generate sufficient air film force. This causes contact between the fingers and the rotor, resulting in a reduced service life of the seal. In view of this situation, this paper proposes a method that can quickly determine whether there is enough gas film force to lift the sealing finger at the design stage. The aeroelastic coupling characteristics of the noncontacting finger seal are studied in conditions where contact exists between the fingers and the rotor. The influences of various environmental and key structural parameters on the number of contact fingers, leakage, bearing force, and friction moment are studied. The results show that the pressure difference, eccentricity, and key design parameters have important effects on the number of contact fingers. The effect of rotation speed is relatively small. This paper provides a time-efficient tool for the design of noncontacting finger seals, which can quickly predict the performance of the sealing system.

Rotordynamic Characteristics of a Novel Labyrinth Seal With Swirl Brakes at Seal Entrance and Cavity

Abstract Annular gas seals used in turbomachinery are key elements to ensure a high machine efficiency, due to their effect on the leakage flow. As the most common type of annular gas seals, labyrinth seal is widely used as end and center balance drum, interstage, shaft end, and impeller eye seals. However, labyrinth seals have been confirmed to be a major source of destabilizing forces resulting in rotordynamic instability problems. The destabilizing cross-coupling forces, the major mechanism of inducing an instability vibration, are related to swirl velocity in labyrinth seal cavity. Installing swirl brake devices at the seal entrance is efficient to improve the seal stability by suppressing the inlet preswirl velocity. The swirl velocity downstream inlet swirl brakes can be reduced obviously, and it is usually less than the linear velocity of the rotor surface; then, the swirl velocity in seal cavity increases from inlet to outlet as a result of the viscous effect of rotating surface. In this article, to improve the rotordynamic performance of the labyrinth seal, a novel labyrinth seal (design 3), which possesses inlet swirl brakes at the seal entrance and swirl-reversal brakes in the fourth cavity, was designed. The effect of the swirl-reversal brakes on the seal rotordynamic characteristics was numerically investigated at two preswirl velocities and two rotational speeds. A detailed comparison was conducted for the rotordynamic characteristics of this novel labyrinth seal with those of a no-brake configuration (design 1) and an inlet swirl brakes configuration (design 2). The transient computational fluid dynamics (CFD) method based on the multifrequency elliptical whirling orbit model was used to predict frequency-dependent rotordynamic coefficients for these three seal configurations. The accuracy and availability of the present transient numerical method were demonstrated based on the experimental data. In general, for all three seal designs, the rotational speed and the inlet preswirl velocity have a significant effect on the cross-coupling stiffness and effective damping, but a weak influence on the direct stiffness and direct damping, where the effect of the inlet preswirl velocity is more remarkable. For the low inlet preswirl velocity w = 10 m/s case, compared to the original seal design 2, the magnitude of the negative cross-coupling stiffness shows an obvious increase (by ∼314% and ∼218% for the n = 6 krpm and n = 9 krpm case, respectively) for design 3. Compared to the seal design 1 with no swirl brakes, the effective damping increases by ∼33% for design 2 and by ∼130% for design 3 at the rotational speed of 6 krpm. At the high inlet preswirl velocity of w = 106 m/s, the labyrinth seals with no swirl brake (design 1) and with only inlet swirl brake (design 2) both produce the destabilizing positive cross-coupling stiffness and a crossover frequency (175 Hz for the seal design 1, 28 Hz for the seal design 2) below which the effective damping is negative for the n = 9 krpm case; however, design 3 still possesses the stabilizing negative cross-coupling stiffness (below 240 Hz) and the positive effective damping throughout whole frequency range for the n = 9 krpm case. The present novel labyrinth seal (design 3) produces the largest effective damping, followed by the seal design 2 and then the seal Design 1, for all rotational speed and inlet preswirl cases. Therefore, the novel labyrinth seal (design 3) possesses better rotordynamic characteristics than other two seals.

An assessment on the effectiveness of the sanitary seal in protecting boreholes from contamination: A case of Mbare Suburb, Harare

Zimbabwe is projected to suffer water stress by 2025. Water availability is decreasing in the capital Harare, particularly in high density settlements where people rely mainly on boreholes. Anthropogenic pollution and poorly constructed boreholes lead to high levels of bacteriological contamination of borehole water sources, posing an increased risk of diarrheal disease for beneficiaries. To mitigate the risk of recurrent diarrheal outbreaks, Médecins Sans Frontiers piloted the incorporation of borehole sanitary seal in accordance with the local geology while drilling new boreholes in Harare. This study compared physical, chemical and bacteriological parameters between boreholes with two different sanitary seal types and no sanitary seal in Harare's Mbare suburb. 14 boreholes were classified into three categories based on the installed sanitary seal. Water quality analysis were conducted to describe physical, chemical and bacteriological parameters across three categories. The three categories included 4 boreholes with no seal, 6 with 3–6 m seal (random seal) and 4 with 18–25 m seal (proper seal; done in accordance with local geology). Water samples were collected between February 2019 to January 2020 in 3 sampling periods and analysed according to APHA standards. Groundwater vulnerability assessment to map pollution risk of the study areas showed 80% of the study area had high vulnerability. Results of water quality analysis revealed that only boreholes with 18–25m sanitary seal satisfied the WHO guidelines for drinking water. This study suggests that local geology should be considered to install borehole sanitary seals for contaminated shallow water aquifers in urban settlements.

CFD Flow Analysis of the Influence of Rotor Seals in a Cantilever Microturbine

The article describes the results from the research and development of a cantilever microturbine designed for ORC power plants. The main objective of the paper was to compare different types of rotor seals and their effect on the turbine efficiency and rotor forces. The turbine stage and the numerical models used in the CFD system NUMECA FINE/Turbo are briefly described. The results are compared with the values obtained from measurements and previous simulations. The results show a relatively limited influence of the seal design on the turbine efficiency. The results also show the effect of the seal on the rotor axial force.

Sealing Ability of Obturation with Different Sealers Applied Over Apically Separated Rotary File - Retrograde Bacterial Leakage Study.

Background and Aims. Retrieval of separated rotary file may not be possible many times. Then sealing of coronal root canal system depends on sealing ability of root canal sealers. The type of seal to be obtained should be bacterial-tight seal. Hence it is important to evaluate the sealing ability of obturation with different newer sealers with separated file in apical 3rd of root canals with bacterial penetration method using e.fecalis.Methods:Forty six human mandibular molars extracted for periodontal reasons were collected. After Decoronation of teeth Protaper rotary S1 files (Dentsply Maillefer) were intentionally separated in apical third of canal and obturated with gutta-percha (Prime Dental Products, India) along with zinc oxide eugenol sealer (Dental products of India-Mumbai) in Group I, Nano Zinc oxide eugenol (Nano Research Lab, Jharkand, India) in Group II and MTA sealer (Angelus, Londrina, Brazil) in Group III. Samples were assessed for bacterial leakage with E fecalis for 48 hours. The number of colony forming units was assessed.Results:The values obtained were subjected to one way ANOVA test and significance level was set to 0.05. Group I scored the highest mean value of (6.58), followed by Group II (3.91). The lowest Mean value was with Group III (2.91). However there was no statistical significant difference in Mean values among groups with (p-value 0.05).Conclusion:The mean value of colony forming units in Group III was 2.91, in Group II 3.91 and 6.58 in Group I. None of the groups demonstrated complete bacteria-tight seal.

The Impact of Chinese Seals on the Structure, Design, and Usage of the Īl-Khānids Seals and Coins

Il-Khanid seals and coins are a type of seal featuring figurative patterns typically characterized by the Rectangular style of Kufic script, the absence of figures, extensive use of calligraphy, geometric, and abstract patterns. Although it is based on the Persian seal-carving tradition, the Īl-Khānids seals and coins exhibit various elements from the Chinese seals (印章), and also similar in their style to the Mongolian writing systems. While the Silk Road, the central path for trade and economic purposes, brought together China and Persia, the two nations had strong influences regarding culture, tradition, and religion, and Persian art has applied many Chinese artistic elements, particularly in the art of seal making. Indeed, the historical evidence suggests that the Mongolian Empire employed the Chinese seals (印章) throughout their territory, stretching from China to Persia.
 The intercultural influences through the Silk Road seem to be well-rooted in Central Asia, and for the first time, Chinese culture is seen abundantly in the Īl-Khānids seal history, as well as the Rectangular style of Kufic script on the seals and coins, influenced by the Uighur script. This paper uses an interdisciplinary approach to analyse the Chinese and the Īl-Khānids seals and coins to survey transmission of the Chinese tradition through Silk Road cultural exchanges. The results show that there exists a strong possibility that the manner in which the writing of Arabic characters in the Rectangular Kufic writing system was inserted at the top to the bottom unexpectedly followed the style of Mongolian words.

Failure analysis and improvement measures of airplane actuator seals

Hydraulic actuators are an important executive component of modern aircraft and are typically characterized by a reciprocating sealing form. Sealing failure affects the implementation of aircraft missions and flight safety. To determine the main cause for sealing failure of the ACGT-HP combined rod seal in an aircraft actuator, taking the new seal as the control group, compare and analyze the failure and non-failure combined rod seals under the same working conditions for approximately the same time. By means of microscopic examination, physical performance testing and chemical composition analysis, eight ACGT-HP seal failure reasons that act synergistically are summarized and preventive improvement measures are proposed. It is concluded that the main reason for the failure of the combined seal is that the wear of the seal is exacerbated by various inappropriate coupling factors, resulting in the rapid reduction of contact stress and seal failure. By putting forward the key points of seal design and assembly, a universal failure analysis method from macro to micro is found, which can be used for various types of combined seals to guide the design and application of the ACGT-HP seals.

Proposal of a new classification: "sealed type" postinfarction left ventricular free wall rupture.

Postinfarction leftventricular free wall rupture (FWR) has been classified into blow-out type and oozing type. However, considering past papers, oozing type included the cases in which the bleeding had spontaneously stopped or sealed, and the distinction between blow-out type and oozing type was not always clear. We classified FWR into the BO type (combination of blow-out type and oozing type) with continuous bleeding and sealed type and clarified the pathophysiology of the sealed type. Thirty-five patients who underwent surgical treatment for FWR during the past 21years were retrospectively evaluated. Twenty-one patients (60%) were sealed. Comparing the sealed type with the BO type, the incidence of sudden collapse with acute onset was significantly lower (sealed type; 62%, BO type; 100%, P = 0.0118), and there were more cases of transport from outside the hospital (76%, 43%, P = 0.0453). Significantly few cases had electro-mechanical dissociation immediately before surgery (10%, 71%, P = 0.0001). In the sealed type, median sternotomy was performed in 9 patients (43%), and subxiphoid drainage was performed in 12 (57%). Fifteen patients (71%) were supported by IABP postoperatively, and re-rupture occurred in 3 patients without IABP. Long-term outcomes were significantly better in the sealed type than in the BO type. Sixty percent of postinfarction ventricular free wall rupture was the sealed type. Median sternotomy and sutureless repair with postoperative IABP support were reliable treatments. Subxiphoid drainage and strict blood pressure control with IABP may be acceptable surgical strategies in elderly, frail patients.

Analysis of the Sealing Performance of a Concave O-Ring Groove

In industrial plants and pressurized equipment, leakage control and prevention are key tasks in preventive maintenance programs. The most critical element in these types of equipment is the seals. Several types of seals are used and the most popular are flat seals and O-rings. Two conditions affect the proper functioning of the seals: the mounting configuration and the initial loading parameters during operation. In this work, the analysis of the mechanical and leakage behaviour of the O-ring seal, when installed either in a cylindrical concave groove or in a rectangular one, is presented. Two finite element models were developed with Ansys software to study the behaviour of the assemblies in both cases when the clamping load is applied and when the assembly is pressurized. The results of the numerical models are compared to the analytical approach based on Hertz's contact theory. This study shows that the use of a cylindrical concave groove for mounting elastomeric O-rings can improve sealing in pressurized systems.

An Analytical Two-Phase Flow Model for Prediction of Leakage in Wet Gas Labyrinth Seals and Pocket Damper Seals. Is Simplicity Still Desired?

Abstract Current and upcoming two-phase pump and compression systems in subsea production facilities must demonstrate long-term operation and continuous availability. Annular pressure seals, limiting secondary flow, also influence the dynamic stability of turbomachinery. Hence, it becomes paramount to quantify the leakage and dynamic force coefficients of annular seals operating with two-phase flow, a liquid in gas mixture or wet gas. Until now, a simple model for labyrinth seals (LSs) and the more modern pocket damper seals (PDSs) is not available, though these seal types find wide applications in subsea machinery. The paper develops a simple analytical model predicting the leakage and cavity pressures for LSs and PDSs operating with two-phase flow. The model adapts Neumann’s leakage equation for use with the physical properties of a homogeneous two-phase flow mixture. Predictions of leakage for a four-blade, eight-pocket, fully partitioned PDS operating under a low supply pressure (PS = 2.3 bar and 3.2 bar) and a low rotor speed equal to 5250 rpm (surface speed = 35 m/s) agree well with experimental results procured for both a pure gas and a wet gas conditions (2.2% in liquid volume). Predicted leakage and cavity pressures also agree with those found by a multimillion node computational fluid dynamics (CFD) model. For an eight-blade, sixteen-pocket PDS supplied with air at PS = 62.1 bar, discharge pressure Pa = 31.1 bar, and rotor speed of 15 krpm (surface speed = 91 m/s), the analytical model predicts leakage that is just 2% larger than a published CFD prediction. For the PDS supplied with an oil in gas mixture having gas volume fraction βS = 0.92–0.98, the simple model delivers leakage that is up to ∼6% lower than published CFD results. An analysis of the two-phase leakage predictions via a modified flow factor reveals a loss coefficient (cd) impervious to the range of supply and discharge pressures considered and growing in proportion to the liquid volume fraction (LVF). Throughout the life of an oil well that sees radical changes in gas and liquid composition as well as pressure conditions, the expedient model, quick and accurate to estimate leakage in wet gases seals, can be readily integrated into an engineering routine or practice.

Experimental Study on the Leak Mechanism of the Ferrofluid Seal in a Water Environment

The advantages of magnetic fluid seals, such as low friction moment, high tightness, and high durability, have been known for many years. However, they are used particularly in air or vacuum environments and the application of this type of seal in water still remains a problem. This is mainly due to the friction occurring between the two fluids and interfacial instability. This publication focuses on investigating the influence of magnetic fluid properties on the mechanism of pressure transfer between sealing stages. The main aim was to better understand the leak mechanism in this type of seal and to be able to select ferrofluids (FFs) resistant to water for long-term operation after short-term testing. The tested seals rotated over 4.3 million times without failure. The results of the research carried out are recommendations for the selection of magnetic fluid, sealing stage width, and FF volume.

Coordinating contributions in crowdfunding for sustainable entrepreneurship

Crowdfunding has become a serious opportunity for financing sustainable entrepreneurship. However, funders oftentimes compete with several similar projects for funding. In crowdfunding, projects are only realized if they reach a minimum funding threshold, and this means that funders need to coordinate to reach such a threshold. In this study, we examine how different types of sustainability seals help solve this coordination problem. We simulate a crowdfunding situation using a threshold public goods laboratory experiment. Our results show that the choice of a signal is sensitive to the type of crowdfunding project. For a sustainability project, a non-governmental seal is a better match. Our findings offer new insights for innovators, entrepreneurs, and institutions on how to obtain contributions for sustainability projects and ultimately bring more of this type of project to life.