Inventions

Editorial

3 pages, 190 KiB

Open AccessEditorial

Editorial for Special Issue “Perspectives and Challenges in Doctoral Research—Selected Papers from the 9th Edition of the Scientific Conference of the Doctoral Schools from the “Dunărea de Jos”

by Eugen Rusu and Gabriela Rapeanu

Inventions 2022, 7(2), 33; https://doi.org/10.3390/inventions7020033 - 28 Mar 2022

Viewed by 2523

Abstract

This Editorial is dedicated to the 9th edition of the Scientific Conference organized by the Doctoral Schools of “Dunărea de Jos” University of Galati (SCDS-UDJG), which was organized in June 2021 in Galati (Romania) [...] Full article

(This article belongs to the Special Issue Perspectives and Challenges in Doctoral Research—Selected Papers from the 9th Edition of the Scientific Conference of the Doctoral Schools from the “Dunărea de Jos” University of Galaţi)

Research

Jump to: Editorial, Review

11 pages, 2474 KiB

Open AccessArticle

An Analysis of the Wind Parameters in the Western Side of the Black Sea

by Laura-Ionela Nedelcu and Eugen Rusu

Inventions 2022, 7(1), 21; https://doi.org/10.3390/inventions7010021 - 2 Feb 2022

Cited by 7 | Viewed by 3389

Abstract

In the present research, an overview of the wind climate on the northwestern coast of the Black Sea basin is assessed, using a total of 6 years of data (2015–2020) provided by the National Institute of Marine Geology and Geoecology (GeoEcoMar). It is [...] Read more.

In the present research, an overview of the wind climate on the northwestern coast of the Black Sea basin is assessed, using a total of 6 years of data (2015–2020) provided by the National Institute of Marine Geology and Geoecology (GeoEcoMar). It is well known that the enclosed/semi-enclosed basins are complex environments and to accurately represent the features of wind and wave are necessary high resolution spatial fields. For the Black Sea, which is an enclosed basin with complicated regional geography, the main weather parameters reported (wind direction, wind speed, air temperature, air pressure) give a more comprehensive picture of how energetic the area of interest is, and represent the features of the Black Sea’s diversified marine environment. Finally, the results obtained in this paper cover a broad range of applications in marine studies, being useful for future research in the area of wind climate in the Black Sea. Full article

(This article belongs to the Special Issue Perspectives and Challenges in Doctoral Research—Selected Papers from the 9th Edition of the Scientific Conference of the Doctoral Schools from the “Dunărea de Jos” University of Galaţi)

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13 pages, 3710 KiB

Open AccessArticle

Introducing the Living Lab Approach in the Coastal Area of Constanta (Romania) by Using Design Thinking

by Catalin Anton, Angela Eliza Micu and Eugen Rusu

Inventions 2022, 7(1), 19; https://doi.org/10.3390/inventions7010019 - 29 Jan 2022

Cited by 6 | Viewed by 3469

Abstract

Living Labs are an innovative concept that combines research, governance, and citizens, using technology and knowledge. Using design thinking techniques as a method of approach, this innovative idea builds a bridge between decision makers and stakeholders, promoting a shared vision of growth and [...] Read more.

Living Labs are an innovative concept that combines research, governance, and citizens, using technology and knowledge. Using design thinking techniques as a method of approach, this innovative idea builds a bridge between decision makers and stakeholders, promoting a shared vision of growth and innovation at the community level. The coastal zone is an extremely dynamic area in terms of human and natural activities. This is a particularly sensitive area to climate change, necessitating ongoing adaptation and mitigating action. This paper aims to introduce the application of the Living lab concept in the management of the coastal area of Constanta (Romania). The concept of the Living Lab means involving citizens along with public bodies and research structures. This new coastal management model will use the design thinking approach and will consider the pressures that exist between the activities that occur in the examined coastal zone. In the study, “Multi-Criteria Analysis of the Mass Tourism Management Model Related to the Impact on the Local Community in Constanța (Romania)”, published in MDPI Inventions on 28 June 2021, a coastal management model was built that took into consideration only the data given by the government. In this paper, the authors aim to expand their research by including data from independent sources, using the concept of a Living Lab. Full article

(This article belongs to the Special Issue Perspectives and Challenges in Doctoral Research—Selected Papers from the 9th Edition of the Scientific Conference of the Doctoral Schools from the “Dunărea de Jos” University of Galaţi)

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18 pages, 6175 KiB

Open AccessArticle

Estimation of the Tower Shape Effect on the Stress–Strain Behavior of Wind Turbines Operating under Offshore Boundary Conditions

by Alexandra Ionelia Diaconita, Gabriel Andrei and Eugen Rusu

Inventions 2022, 7(1), 11; https://doi.org/10.3390/inventions7010011 - 7 Jan 2022

Cited by 5 | Viewed by 6468

Abstract

The metal tower, or the pylon, is one of the most important elements in the construction of a wind turbine. It has the role of supporting the entire wind turbine, and it also allows access for inspection and conducting planned maintenance and repairs. [...] Read more.

The metal tower, or the pylon, is one of the most important elements in the construction of a wind turbine. It has the role of supporting the entire wind turbine, and it also allows access for inspection and conducting planned maintenance and repairs. Moreover, the tower ensures support for the structure and strengthens the whole assembly. It has a particularly important role, as it has to face very severe weather conditions. The present study aims to analyze the forces and moments resulting from the action of the wind on the tower of a wind turbine. Two important load cases are considered, namely, the load under operating conditions and the ultimate load under 50 year wind conditions. For this purpose, cylindrical and conical geometric shapes of the tower were chosen. These were analyzed under the action of both normal and extreme wind speeds. Then, the behavior of the two towers under the action of the wind speed for a location in the Black Sea was analyzed. Finally, in an attempt to make the structure more economical, the thickness of the shell was reduced. Full article

(This article belongs to the Special Issue Perspectives and Challenges in Doctoral Research—Selected Papers from the 9th Edition of the Scientific Conference of the Doctoral Schools from the “Dunărea de Jos” University of Galaţi)

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16 pages, 663 KiB

Open AccessArticle

Analysis of Some Essential Aspects Related to the Navigation Conditions on the Danube River

by Andra Luciana Marcu Turcanu, Liliana Mihaela Moga and Eugen Victor Cristian Rusu

Inventions 2021, 6(4), 97; https://doi.org/10.3390/inventions6040097 - 17 Dec 2021

Cited by 2 | Viewed by 2098

Abstract

The European Union has emphasized the creation of an appropriate framework to optimize the internal market and inland transport waterways, and remove barriers to their wider use. Administrative barriers in the logistics of goods on the Danube waterway and its navigable tributaries constitute [...] Read more.

The European Union has emphasized the creation of an appropriate framework to optimize the internal market and inland transport waterways, and remove barriers to their wider use. Administrative barriers in the logistics of goods on the Danube waterway and its navigable tributaries constitute a significant obstacle to the efficient and sustainable use of the Danube as the region’s central transport hub. The approach proposed in this paper was designed to identify and analyze the relationship between the main variables leading to problematic inland waterway traffic, in this case, on the Danube, and the measures taken by the European Commission to improve it. In terms of the applied research method, “Quality Function Deployment” (QFD), we assign global (overall) and local priority degrees. The proposed framework for adapting QFD as a tool for improving quality and, therefore, performance, aims to identify and prioritize directions for this improvement. The House of Quality (HOQ) is the tool that links areas for improvement to technical requirements. The disclosure of these connections helps identify and prioritize the technical features that will generate the most significant improvements. Full article

(This article belongs to the Special Issue Perspectives and Challenges in Doctoral Research—Selected Papers from the 9th Edition of the Scientific Conference of the Doctoral Schools from the “Dunărea de Jos” University of Galaţi)

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14 pages, 4580 KiB

Open AccessArticle

Study of Resistance to Disturbances of the Main Types of Communication Systems on Board Military Ships Used during Interception or Search and Rescue Missions

by Vasile Solcanu, Marian Gaiceanu and Georgiana Rosu

Inventions 2021, 6(4), 72; https://doi.org/10.3390/inventions6040072 - 27 Oct 2021

Cited by 3 | Viewed by 2981

Abstract

In addition to combat missions, military ships often participate in search-and-rescue missions or interception of ships with refugees or migrants. The communication systems and modes of work that may be used during these missions will be in accordance with the International Convention for [...] Read more.

In addition to combat missions, military ships often participate in search-and-rescue missions or interception of ships with refugees or migrants. The communication systems and modes of work that may be used during these missions will be in accordance with the International Convention for the Safety of Life at Sea (SOLAS). This paper aims to demonstrate by theoretical methods (analytical and numerical) the noise stability of communication systems using analog modulation in high-noise conditions, characteristic of the marine environment. The stability of analog systems employing amplitude (AM), frequency (FM), and phase (PM) modulations is investigated. The analyzed systems are currently under use in distress maritime communications. Full article

(This article belongs to the Special Issue Perspectives and Challenges in Doctoral Research—Selected Papers from the 9th Edition of the Scientific Conference of the Doctoral Schools from the “Dunărea de Jos” University of Galaţi)

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15 pages, 30124 KiB

Open AccessArticle

Insights of Sea Buckthorn Extract’s Encapsulation by Coacervation Technique

by Diana Roman, Nina Nicoleta Condurache (Lazăr), Iuliana Aprodu, Elena Enachi, Vasilica Barbu, Gabriela Elena Bahrim, Nicoleta Stănciuc and Gabriela Râpeanu

Inventions 2021, 6(3), 59; https://doi.org/10.3390/inventions6030059 - 14 Sep 2021

Cited by 7 | Viewed by 2857

Abstract

Sea buckthorn (Hippophae rhamnoides L.) represents a valuable source of biologically active compounds such as carotenoids and polyphenols. High amounts of these substances are found in its fruits, bark, and leaves. However, their bioavailability is limited and must be increased in order [...] Read more.

Sea buckthorn (Hippophae rhamnoides L.) represents a valuable source of biologically active compounds such as carotenoids and polyphenols. High amounts of these substances are found in its fruits, bark, and leaves. However, their bioavailability is limited and must be increased in order to benefit from the properties they exert. Therefore, the purpose of this study was to increase the stability and bioavailability of sea buckthorn fruit’s bioactives. The sea buckthorn’s bioactive compounds were extracted with a solvent combination between glacial acetic acid, acetone, and water on one side and water only on the other side. Afterward, the phytochemicals from the extracts were encapsulated using the coacervation technique, followed by freeze-drying in order to obtain stable powders. The powders were characterized in terms of antioxidant activity, total carotenoids, β-carotene, lycopene, total polyphenol, and total flavonoid content, color, structure, and morphology. The phytochemical stability of the powders and their antioxidant activity was assessed during 270 days of storage at 4 °C. Moreover, the bioavailability of phytochemicals was measured during in vitro simulated digestibility. Our findings provide insights to promote carotenoids and polyphenols from sea buckthorn as bioactive ingredients with multiple purposes. Full article

(This article belongs to the Special Issue Perspectives and Challenges in Doctoral Research—Selected Papers from the 9th Edition of the Scientific Conference of the Doctoral Schools from the “Dunărea de Jos” University of Galaţi)

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15 pages, 2586 KiB

Open AccessArticle

Determination of Atorvastatin with Voltammetric Sensors Based on Nanomaterials

by Ramona Oana Gunache (Roșca), Alexandra Virginia Bounegru and Constantin Apetrei

Inventions 2021, 6(3), 57; https://doi.org/10.3390/inventions6030057 - 12 Aug 2021

Cited by 15 | Viewed by 3256

Abstract

This paper presents an accurate and fast electrochemical method for atorvastatin determination in pharmaceutical products. Two screen-printed sensors, one—carbon based (SPCE) and one based on carbon nanotubes and gold nanoparticles (AuNP-CNT/SPCE) were used during the electrochemical analyses. At all experimental stages, cyclic voltammetry [...] Read more.

This paper presents an accurate and fast electrochemical method for atorvastatin determination in pharmaceutical products. Two screen-printed sensors, one—carbon based (SPCE) and one based on carbon nanotubes and gold nanoparticles (AuNP-CNT/SPCE) were used during the electrochemical analyses. At all experimental stages, cyclic voltammetry was employed, both for the characterization of the sensors and their electrochemical behavior, and for quantitative determinations. AuNP-CNT/SPCE has showed an extended active area, higher intensity peaks, better reversibility and lower background current than the unmodified sensor. For atorvastatin quantification, a calibration curve has been developed within the 1.2–606.25 µM concentration range. A linearity relation between the current of the anodic peak and concentration has been obtained in the range 1.2–53.33 µMfor both sensors. With the AuNP-CNT/SPCE sensor, low values of limit of detection, LOD (1.92 × 10⁻⁷ M) and limit of quantification, LOQ (6.39 × 10⁻⁷ M) have been obtained, which demonstrates the feasibility of the method of determining atorvastatin from real samples. Atorvastatin amount has been successfully determined from pharmaceutical products using AuNP-CNT/SPCE. The results were similar to the manufacturer’s specifications regarding the dosage per tablet and to the concentrations obtained by applying the FTIR spectrometric method. Full article

(This article belongs to the Special Issue Perspectives and Challenges in Doctoral Research—Selected Papers from the 9th Edition of the Scientific Conference of the Doctoral Schools from the “Dunărea de Jos” University of Galaţi)

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13 pages, 3180 KiB

Open AccessArticle

Development of a Novel Sensor Based on Polypyrrole Doped with Potassium Hexacyanoferrate (II) for Detection of L-Tryptophan in Pharmaceutics

by Ancuța Dinu and Constantin Apetrei

Inventions 2021, 6(3), 56; https://doi.org/10.3390/inventions6030056 - 28 Jul 2021

Cited by 9 | Viewed by 3207

Abstract

This study describes the development of a new sensor with applicability in the determination and quantification of yjr essential amino acid (AA) L-tryptophan (L-TRP) from pharmaceutical products. The proposed sensor is based on a carbon screen-printed electrode (SPCE) modified with the conductor polymer [...] Read more.

This study describes the development of a new sensor with applicability in the determination and quantification of yjr essential amino acid (AA) L-tryptophan (L-TRP) from pharmaceutical products. The proposed sensor is based on a carbon screen-printed electrode (SPCE) modified with the conductor polymer polypyrrole (PPy) doped with potassium hexacyanoferrate (II) (FeCN). For the modification of the SPCE with the PPy doped with FeCN, the chronoamperometry (CA) method was used. For the study of the electrochemical behavior and the sensitive properties of the sensor when detecting L-TRP, the cyclic voltammetry (CV) method was used. This developed electrode has shown a high sensibility, a low detection limit (LOD) of up to 1.05 × 10⁻⁷ M, a quantification limit (LOQ) equal to 3.51 × 10⁻⁷ M and a wide linearity range between 3.3 × 10⁻⁷ M and 1.06 × 10⁻⁵ M. The analytical performances of the device were studied for the detection of AA L-TRP from pharmaceutical products, obtaining excellent results. The validation of the electroanalytical method was performed by using the standard method with good results. Full article

(This article belongs to the Special Issue Perspectives and Challenges in Doctoral Research—Selected Papers from the 9th Edition of the Scientific Conference of the Doctoral Schools from the “Dunărea de Jos” University of Galaţi)

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19 pages, 11993 KiB

Open AccessArticle

Implementation Aspects Regarding Closed-Loop Control Systems Using Evolutionary Algorithms

by Viorel Minzu, Saïd Riahi and Eugen Rusu

Inventions 2021, 6(3), 53; https://doi.org/10.3390/inventions6030053 - 21 Jul 2021

Cited by 9 | Viewed by 2494

Abstract

When an optimal control problem requires an important computational effort, a metaheuristic algorithm (MA) can be a useful approach. An MA is conceived to solve a specific optimal control problem having a characteristic objective function. This algorithm solely yields only an optimal offline [...] Read more.

When an optimal control problem requires an important computational effort, a metaheuristic algorithm (MA) can be a useful approach. An MA is conceived to solve a specific optimal control problem having a characteristic objective function. This algorithm solely yields only an optimal offline solution. The desideratum to have a closed-loop implementation can be fulfilled through a supplementary “tool”, the Receding Horizon Control (RHC) structure. This paper addresses a particular case and integrates Evolutionary Algorithms into the RHC structure. The main objective is to propose a general harmonization between the Controller of the closed loop and the Evolutionary Algorithm. Some details concerning the implementation of the closed loop and Controller are described. The impact of the RHC’s prediction technique upon the control sequences’ encoding is also analyzed. Two general structure Controllers are proposed, one of them conceived to cope with restrictive time constraints. Practical ideas have been illustrated through a case study: the well-known optimal control of a fed-batch reactor for ethanol production. This time, our implementation achieves a closed-loop solution. The results from the programs and simulation series validate the Controllers, EAs, and the closed-loop structure. Generally speaking, the association between RHC and EA can be a realistic solution to optimal process control. Full article

(This article belongs to the Special Issue Perspectives and Challenges in Doctoral Research—Selected Papers from the 9th Edition of the Scientific Conference of the Doctoral Schools from the “Dunărea de Jos” University of Galaţi)

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11 pages, 2021 KiB

Open AccessArticle

Optimization of Betalain Pigments Extraction Using Beetroot by-Products as a Valuable Source

by Silvia Lazăr (Mistrianu), Oana Emilia Constantin, Nicoleta Stănciuc, Iuliana Aprodu, Constantin Croitoru and Gabriela Râpeanu

Inventions 2021, 6(3), 50; https://doi.org/10.3390/inventions6030050 - 14 Jul 2021

Cited by 21 | Viewed by 8318

Abstract

(1) Background: This study is designed to extract the bioactive compounds from beetroot peel for future use in the food industry. (2) Methods: Spectrophotometry techniques analyzed the effect of conventional solvent extraction on betalains and polyphenolic compounds from beetroot peels. Several treatments by [...] Read more.

(1) Background: This study is designed to extract the bioactive compounds from beetroot peel for future use in the food industry. (2) Methods: Spectrophotometry techniques analyzed the effect of conventional solvent extraction on betalains and polyphenolic compounds from beetroot peels. Several treatments by varying for factors (ethanol and citric acid concentration, temperature, and time) were applied to the beetroot peel samples. A Central Composite Design (CCD) has been used to investigate the effect of the extraction parameters on the extraction steps and optimize the betalains and total polyphenols extraction from beetroot. A quadratic model was suggested for all the parameters analyzed and used. (3) Results: The maximum and minimum variables investigated in the experimental plan in the coded form are citric acid concentration (0.10–1.5%), ethanol concentration (10–50%), operating temperature (20–60 °C), and extraction time (15–50 min). The experimental design revealed variation in betalain content ranging from 0.29 to 1.44 mg/g DW, and the yield of polyphenolic varied from 1.64 to 2.74 mg/g DW. The optimized conditions for the maximum recovery of betalains and phenols were citric acid concentration 1.5%, ethanol concentration 50%, temperature 52.52 °C, and extraction time 49.9 min. (4) Conclusions: Overall, it can be noted that the extraction process can be improved by adjusting operating variables in order to maximize the model responses. Full article

(This article belongs to the Special Issue Perspectives and Challenges in Doctoral Research—Selected Papers from the 9th Edition of the Scientific Conference of the Doctoral Schools from the “Dunărea de Jos” University of Galaţi)

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12 pages, 2670 KiB

Open AccessArticle

Impact of Wall Materials on Physico-Chemical Properties and Stability of Eggplant Peels Anthocyanin Hydrogels

by Nina-Nicoleta Condurache (Lazăr), Mihaela Turturică, Elena Enachi, Vasilica Barbu, Gabriela-Elena Bahrim, Nicoleta Stănciuc, Constantin Croitoru and Gabriela Râpeanu

Inventions 2021, 6(3), 47; https://doi.org/10.3390/inventions6030047 - 29 Jun 2021

Cited by 4 | Viewed by 2782

Abstract

In this study, eggplant peel extract was used to obtain hydrogels. Two experimental variants were realized by varying the wall materials. Whey proteins isolate (WPI), citrus pectin (P), and sodium carboxymethylcellulose (CMCNa) were used as wall materials. The microcapsules were obtained by the [...] Read more.

In this study, eggplant peel extract was used to obtain hydrogels. Two experimental variants were realized by varying the wall materials. Whey proteins isolate (WPI), citrus pectin (P), and sodium carboxymethylcellulose (CMCNa) were used as wall materials. The microcapsules were obtained by the gelation technique, followed by freeze-drying in order to obtain powders. Both experimental variants were analyzed in terms of phytochemical content, antioxidant activity, storage stability, and in vitro digestibility. Additionally, confocal microscopy was used to observe the encapsulation of the bioactive compounds from the eggplant peel extract into the selected matrices. The encapsulation efficiency of the powders varied from 64.67 ± 0.68% for variant 1 (V1) to 96.44 ± 3.43% for variant 2 (V2). Both powders presented high bioactive compound content with high antioxidant activity. V2 showed the highest stability within 28 days of storage, but also in the simulated digestive system. Full article

(This article belongs to the Special Issue Perspectives and Challenges in Doctoral Research—Selected Papers from the 9th Edition of the Scientific Conference of the Doctoral Schools from the “Dunărea de Jos” University of Galaţi)

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17 pages, 5250 KiB

Open AccessArticle

Multi-Criteria Analysis of the Mass Tourism Management Model Related to the Impact on the Local Community in Constanta City (Romania)

by Catalin Anton, Angela-Eliza Micu and Eugen Rusu

Inventions 2021, 6(3), 46; https://doi.org/10.3390/inventions6030046 - 28 Jun 2021

Cited by 2 | Viewed by 3773

Abstract

Traditionally and socially, the tourism in Constanta is considered to be important to the local economy. Sun and beach locations are both a draw for locals and tourists to the city, on the Black Sea. However, vacation-oriented activities in the city only have [...] Read more.

Traditionally and socially, the tourism in Constanta is considered to be important to the local economy. Sun and beach locations are both a draw for locals and tourists to the city, on the Black Sea. However, vacation-oriented activities in the city only have a seasonal cycle. In this paper, we proposed to analyze the mass tourist activity in Constanta, taking into account economic, social, and environmental conditions. Additionally, we attempted to build a model based on the data available. The model was developed using a PESTEL analysis to determine the supportability factor of the indicators identified. We also set out to create a projection of the activities proposed for analysis by 2050. To create a model for coastal areas, the data used in this research must be accurate and consistent. Furthermore, correctly identifying indicators and their relationships is a critical step in conducting a thorough study. Last but not least, finding the calculation coefficient for the activity in question is critical, as collecting data from various activities might be challenging when trying to find a feasible model. Full article

(This article belongs to the Special Issue Perspectives and Challenges in Doctoral Research—Selected Papers from the 9th Edition of the Scientific Conference of the Doctoral Schools from the “Dunărea de Jos” University of Galaţi)

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17 pages, 9635 KiB

Open AccessArticle

Assessment of the Wind Energy Potential along the Romanian Coastal Zone

by Alina Girleanu, Florin Onea and Eugen Rusu

Inventions 2021, 6(2), 41; https://doi.org/10.3390/inventions6020041 - 4 Jun 2021

Cited by 9 | Viewed by 3576

Abstract

The present work aims to provide a comprehensive picture of the wind energy potential that characterizes the Romanian coastal environment using in situ measurements and reanalysis of wind data (ERA5) that cover a 42–year time interval (1979–2020). A total of 16 reference points [...] Read more.

The present work aims to provide a comprehensive picture of the wind energy potential that characterizes the Romanian coastal environment using in situ measurements and reanalysis of wind data (ERA5) that cover a 42–year time interval (1979–2020). A total of 16 reference points (both land and offshore) equally distributed along the Romanian sector are used to evaluate the local wind energy potential, targeting in this way several sites where a renewable wind project could be established. Compared to the in situ measurements (land points), the ERA5 dataset underestimates the wind speed by at least 11.57%, this value increasing as we approach the coastline. From the analysis of the spatial maps, it is likely that the wind speed steadily increases from onshore to offshore, with a sharp variation near the coastline being reported. Furthermore, the assessment of some state-of-the-art offshore wind turbines was conducted using 12 systems defined by rated capacity ranging from 2 to 10 MW. Some scenarios were proposed to identify sustainable offshore wind projects to be implemented in the Romanian coastal zone based on these results. Full article

(This article belongs to the Special Issue Perspectives and Challenges in Doctoral Research—Selected Papers from the 9th Edition of the Scientific Conference of the Doctoral Schools from the “Dunărea de Jos” University of Galaţi)

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8 pages, 1095 KiB

Open AccessArticle

Roller Profiling for Generating the Screw of a Pump with Progressive Cavities

by Nicuşor Baroiu, Georgiana-Alexandra Moroşanu, Virgil-Gabriel Teodor and Nicolae Oancea

Inventions 2021, 6(2), 34; https://doi.org/10.3390/inventions6020034 - 14 May 2021

Cited by 5 | Viewed by 2916

Abstract

Progressive cavity pumps are used in industry for the circulation of high viscosity fluids, such as crude oil and petroleum products, sewage sludge, oils, salt water, and wastewater. Also known as single screw pumps, these pumps are composed of a single rotor which [...] Read more.

Progressive cavity pumps are used in industry for the circulation of high viscosity fluids, such as crude oil and petroleum products, sewage sludge, oils, salt water, and wastewater. Also known as single screw pumps, these pumps are composed of a single rotor which has the shape of a rounded screw, which moves inside a rubber stator. The stator has an double helical internal surface which, together with the helical surface of the rotor, creates a cavity that moves along the rotor. The movement effect of the cavity inside the stator is the movement of the fluid with a constant flow and high pressure. In this paper, an algorithm for profiling the rollers for generating the helical surface of the pump rotor with progressive cavities is proposed. These rollers are constituted as tools for the plastic deformation of the blank (in case the pump rotor is obtained by volumetric deformation) or for its superficial hardening. Full article

(This article belongs to the Special Issue Perspectives and Challenges in Doctoral Research—Selected Papers from the 9th Edition of the Scientific Conference of the Doctoral Schools from the “Dunărea de Jos” University of Galaţi)

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Review

Jump to: Editorial, Research

33 pages, 6350 KiB

Open AccessReview

Review on Study Methods for Reciprocally Enwrapping Surfaces

by Georgiana Alexandra Moroşanu, Nicuşor Baroiu, Virgil Gabriel Teodor, Viorel Păunoiu and Nicolae Oancea

Inventions 2022, 7(1), 10; https://doi.org/10.3390/inventions7010010 - 7 Jan 2022

Cited by 4 | Viewed by 2412

Abstract

The processing of the piece surfaces involves the transformation of the blank into a piece, the defining characteristics of the surfaces (the form, dimensions, deviations, etc.), depending to a large extent on the parameters of the generated processes of the surfaces. Generating surfaces [...] Read more.

The processing of the piece surfaces involves the transformation of the blank into a piece, the defining characteristics of the surfaces (the form, dimensions, deviations, etc.), depending to a large extent on the parameters of the generated processes of the surfaces. Generating surfaces by enveloping represents a complex problem, this mode of generating being a constant concern of researchers due to its advantages. A very important issue is the cutting edge profiling of the future tool, which will generate the wanted profile of the piece. Throughout time, researchers have studied the problems of enveloping surfaces and stated theorems related to them, based on which practical solutions have been conceive to determine the generating and generated surfaces form. The paper presents an overview on study methods for reciprocally enwrapping surfaces, as well as methods for profiling tools for generating helical surfaces by the kinematic method and by the method of decomposing the helical movement. This review can represent a basis for future research articles and projects. Full article

(This article belongs to the Special Issue Perspectives and Challenges in Doctoral Research—Selected Papers from the 9th Edition of the Scientific Conference of the Doctoral Schools from the “Dunărea de Jos” University of Galaţi)

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21 pages, 4935 KiB

Open AccessReview

An Overview of the Ship Ventilation Systems and Measures to Avoid the Spread of Diseases

by Victor Mihai and Liliana Rusu

Inventions 2021, 6(3), 55; https://doi.org/10.3390/inventions6030055 - 27 Jul 2021

Cited by 15 | Viewed by 27402

Abstract

This article presents a review of the main aspects regarding the current rules of classification societies, standards, and practice regarding the design and construction of ventilation and air conditioning systems for different compartments in different types of ships. In the context of the [...] Read more.

This article presents a review of the main aspects regarding the current rules of classification societies, standards, and practice regarding the design and construction of ventilation and air conditioning systems for different compartments in different types of ships. In the context of the COVID-19 pandemic, this paper also presents the usual practice of the actual heating ventilation and air conditioning (HVAC) systems used on large ships, which recirculate the air between living compartments, in comparison with the new requirements to avoid the risk of spreading diseases. According to the rules, the technical compartments are provided with independent ventilation systems that ensure high air flow rates; therefore, the spread of diseases through this system is not an issue. The living spaces are provided with common ventilation and air conditioning systems that recirculate the air in all compartments served. The current practice of air recirculation in various living rooms leads to the spread of diseases, which should therefore be analyzed and improved by adding high-efficiency particulate air (HEPA) filters and UV disinfection or be replaced with individual systems that provide local heating or cooling without air recirculation between different rooms and fresh air supply with complete evacuation. For existing ships, different solutions should be analyzed such as reducing or cancelling recirculation and increasing filtration. Full article

(This article belongs to the Special Issue Perspectives and Challenges in Doctoral Research—Selected Papers from the 9th Edition of the Scientific Conference of the Doctoral Schools from the “Dunărea de Jos” University of Galaţi)

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