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Abstract

This paper deals with the disturbance rejection, parameter uncertainty cancelation, and the closed-loop stabilization of the water level of the four-tank nonlinear system. For the four-tank system with relative degree one, a new structure of the active disturbance rejection control (ADRC) has been presented by incorporating a tracking differentiator (TD) in the control unit to obtain the derivate of the tracking error. Thus, the nonlinear-PD control together with the TD serves as a new nonlinear state error feedback. Moreover, a sliding mode extended state observer is presented in the feedback loop to estimate the system's state and the total disturbance. The proposed scheme has been compared with several control schemes including linear and nonlinear versions of ADRC techniques. Finally, the simulation results show that the proposed scheme achieves excellent results in terms of disturbance elimination and output tracking as compared to other conventional schemes. It was able to control the water levels in the two lower tanks to their desired value and exhibits excellent performance in terms of Integral Time Absolute Error (ITAE) and Objective Performance Index (OPI).

Open access

Az Európai Unió és a tagállamok válasza a COVID–19 pandémiára – a szabad mozgás jogának közegészségügyi korlátozásai

European Union and Member State Responses to the COVID-19 Pandemic – Restricting the Free Movement of EU citizens on Public Health Grounds

Scientia et Securitas
Authors: Laura Gyeney and Marcel Szabó

Összefoglaló. A szabad mozgás és tartózkodás joga az uniós polgárság alapintézményének egyik leglényegesebb eleme. A 2020-ban kirobbant koronavírus világjárvány következtében az Európai Unió tagállamai az Európai Unió történetében először kénytelenek voltak radikális, korábban nem alkalmazott eszközökkel korlátozni a szabad mozgás és tartózkodás jogát annak érdekében, hogy megakadályozzák a vírus terjedését. A tanulmány keretében a COVID–19 világjárvány miatt bevezetett korlátozások alapulvételével annak vizsgálatára kerül sor, hogy a szabad mozgás joga közegészségügyi okból történő korlátozása milyen sajátosságokkal bír más, az Európai Unió alapszerződéseiben ugyancsak nevesített kivételekhez (közrend, közbiztonság) képest. A tanulmány ugyancsak vizsgálja azt a kérdést, hogy az Európai Unió által kibocsátott digitális zöldútlevél (vakcinaigazolvány) a Sinopharm és Szputynik-V vakcinával beoltott uniós polgárok számára is biztosítandó-e az uniós jog rendelkezései alapján.

Summary. The right of free movement of EU citizens is the cornerstone of Union citizenship. To control the spread of coronavirus (COVID-19) and to protect the health and well-being of all Europeans, Member States gave a surprisingly quick response, taking unilateral restrictive measures affecting the operation of the internal market in an unprecedented way. On the one hand they have implemented serious travel restrictions at internal borders of the EU. On the other hand, several States have coupled travel bans/restrictions with a temporary reintroduction of border controls at their borders with other Members of the Schengen Area. During the first wave of the pandemic, altogether 17 Schengen States sent notifications regarding the reintroduction of border controls, which is particularly disheartening given that the lifting of EU internal border controls in the Schengen Area is one of the integration’s greatest achievements.

There is no doubt that the Member States’ restrictions on free movement detailed in the paper are well-founded from the point of view of both public international law and European law. As to how they should be put into practice: that is another issue. Still, it is the preferential role of free movement as a part of integration that requires a deeper examination of controversial measures to ascertain whether these are in compliance with EU legal principles. Among the elements to be reviewed are proportionality and the prohibition on discrimination.

It is beyond doubt that COVID-19 can definitely be regarded as a ‘disease with epidemic potential’ that can justify restrictions on free movement. However, the question arises whether Article 29 TFEU provides for the introduction of public health restrictions with general effect. In other words, does it allow for restrictions not based on individual assessment, as opposed to individual threats to public policy and public security? In answering the above question the paper puts a special emphasis on the delimitation of Member States’ public health and public policy/security justifications.

At the time of writing (June 2021) several Member States have already started to issue EU Covid-19 passports. The article also seeks answer to the question whether the Digital Green Certificate could (or, at least, should) be provided for Union citizens vaccinated with Sinopharm or Sputnik-V (vaccines approved by Hungary as a Member State, under European Union law).

Open access

Abstract

A new two-level hierarchical approach to control the trolley position and payload swinging of an overhead crane is proposed. At the first level, a simple mathematical pendulum model is investigated considering the time delay due to the use of a vision system. In the second level, a chain model is developed, extending the previous pendulum model considering the vibration of the suspending chain. The relative displacement of the payload is measured with a vision sensor, and the rest of the state-space variables are determined by a collocated observer. The gain parameters related to the state variables of the chain vibration are determined by the use of a pole placement method. The proposed controller is verified by numerical simulation and experimentally on a laboratory test bench.

Open access

Pandémia és különleges jogrend Magyarországon

Pandemic and law of emergency in Hungary

Scientia et Securitas
Authors: Álmos Ungvári and István Sabjanics

Összefoglaló. A tanulmány a COVID–19 pandémiára adott jogalkotói lehetőségeket és válaszokat elemzi, külön figyelmet fordítva a vonatkozó hazai jogfejlődésre. A szerzők elméleti síkon haladva, de gyakorlati példákkal szemléltetve értelmezik a hazai megoldásokat, amelyeket a pandémiás válság kezelésére alkalmaztak az államok. Az alkalmazott megoldásoknak kettős feltételnek kell megfelelniük: a jogállamisági és hatékonysági szempontoknak egyidejűleg kell érvényesülniük. A demokratikus intézményeknek mindebben aktív szerepük van, ugyanakkor lényeges a meghozott intézkedések politikai elfogadottsága is.

Summary. The essay displays the possibilities and answers of the legislature and the Government of Hungary regarding the COVID-19 pandemic, with a special focus on the Hungarian constitutional traditions and development. The essay reaches out from the theoretical for practical reassurance primarily through solutions used in Hungary and secondarily in other European countries. Displaying the struggles of solution seeking in Hungary and other European countries provides a platform for a much-needed comparative approach. These practices must comply with two conditions: maintaining the rule of law and effectiveness, both of which have to prevail simultaneously. Like in the case of the delicate and ever balancing antiterrorist solutions of western democracies, two very different questions of ‘How can we survive?’ and ‘How can our way of life prevail in the end?’ must be answered with the same answer. The democratic institutions have a crucial role, and with that role these institutions have to be continuously active. In times of grave danger, with a real threat to human life, an emergency with the possibility of such a devastation that paralyses or eliminates state and society, the original role of democratic institutions to serve the people is enhanced. The political acceptance (legitimacy) of the emergency measures taken during the pandemic can make a great difference, but the question of legitimacy itself, favorable as it should be, need not be the most crucial question regarding emergency laws. Introducing emergency legislation is based on some level of real or anticipated threat. The focus and only real goal of emergency legislation, by definition, must always be ensuring the safe return to normal or peacetime legislation. So we can say with confidence that functioning democratic institutions provide a much better chance of a safe and timely return to normalcy and leaving pandemic restrictions behind.

Open access
International Review of Applied Sciences and Engineering
Authors: N. ArikaraVelan, V. Deepak, N. Dhinesh Kumar, G. Muthulingam, S. Vanitha, P. Karthigai Priya, and Sachin Sabariraj

Abstract

In this study, vermicompost is replaced for fine aggregate in geopolymer concrete (GPC). Initially mix design is made for GPC and mix proportion is proposed. The vermicompost is replaced at 5%, 10%, 15% and 20% with M sand in GPC. Result indicates the 5% replacement with vermicompost based geopolymer concrete (GPVC) has the compressive strength of 32 N mm−2 (M30 grade) whereas the compressive strength of control specimen made with GPC is 37 N mm−2. Other replacement shows 21 N mm−2, 14 N mm−2 and 11 N mm−2 respectively. The 5% replaced concrete cubes and control specimen are tested at an elevated temperature of 200°C, 400°C, 600°C and 800°C and compared with the control specimen. There is no significant difference observed in weight lost at control (GPC) and GPVC specimen. An elevated temperature, the weight loss is almost 4% at 200°C because of expulsion of water from the concrete. Afterwards only 2% weight loss is observed in remaining elevated temperature. The compressive strength loss is observed at an elevated temperature in GPC and GPVC specimen because of thermal incompatibility between aggregate and the binder. EDX results show M sand and compost contains Si, Al, C, Fe, Ca, Mg, Na and K and it is similar in the elemental composition and SEM image confirms vermicompost contains fine particles.

Open access
International Review of Applied Sciences and Engineering
Authors: N. ArikaraVelan, V. Deepak, N. Dhinesh Kumar, G. Muthulingam, S. Vanitha, P. Karthigai Priya, and Sachin Sabariraj

Abstract

In this study, vermicompost is replaced for fine aggregate in geopolymer concrete (GPC). Initially mix design is made for GPC and mix proportion is proposed. The vermicompost is replaced at 5%, 10%, 15% and 20% with M sand in GPC. Result indicates the 5% replacement with vermicompost based geopolymer concrete (GPVC) has the compressive strength of 32 N mm−2 (M30 grade) whereas the compressive strength of control specimen made with GPC is 37 N mm−2. Other replacement shows 21 N mm−2, 14 N mm−2 and 11 N mm−2 respectively. The 5% replaced concrete cubes and control specimen are tested at an elevated temperature of 200°C, 400°C, 600°C and 800°C and compared with the control specimen. There is no significant difference observed in weight lost at control (GPC) and GPVC specimen. An elevated temperature, the weight loss is almost 4% at 200°C because of expulsion of water from the concrete. Afterwards only 2% weight loss is observed in remaining elevated temperature. The compressive strength loss is observed at an elevated temperature in GPC and GPVC specimen because of thermal incompatibility between aggregate and the binder. EDX results show M sand and compost contains Si, Al, C, Fe, Ca, Mg, Na and K and it is similar in the elemental composition and SEM image confirms vermicompost contains fine particles.

Open access
Agrokémia és Talajtan
Authors: Birkás Márta, Balla István, Gyuricza Csaba, Kende Zoltán, Kovács Gergő Péter, and Percze Attila

A magyar talajművelésben a kezdetektől az 1900-as évek közepéig a hagyományos szántásos rendszerek domináltak. Az ekék tökéletesedése révén a mélyebb szántások hozzájárultak a talajminőség romlásához.

Az 1900-as évek első évtizedeiben a külföldön kidolgozott művelési módszerek még kevesek érdeklődését keltették fel, azonban a szántásnál kedvezőbb körülmények létrehozása érdemi figyelmet keltett.

Az 1970-es évektől a talajvédő művelés Magyarországon is kedvező fogadtatásra talált. Kísérletekkel igazolódott, hogy a direktvetés előnyei – folyamatosság esetén – a hatodik-hetedik évtől észlelhetők. A mulcshagyó művelés kultivátor alkalmazása esetén rövidebb idő alatt nyújtotta a várt talajvédelmi előnyöket, ennek tudható be a gyorsabb terjedése. A kultivátoros művelés értékét a felszínvédő mulcshagyás, a talajminőség megóvás és a biológiailag aktív talaj erősítette meg.

Az időjáráshoz kapcsolható szélsőségek megjelenése az 1980-as évektől újabb művelési megoldások felé fordították a figyelmet. A talajlazítás a vízbefogadás és tárolás, a mulcshagyás, valamint a növények mélyebb gyökerezése révén került a korábbinál szélesebb körű alkalmazásra. A sávos művelési rendszer a nemzetközileg bizonyított eredmények hátterével számos magyar gazdálkodónál is sikeressé vált.

A magyar talajművelés előrehaladásában a talajközpontú szemlélet kiszélesedése, a növényközpontú szemlélet felváltása révén eredményezett kedvező változásokat a talajállapot javulásában.

Tekintettel a talajok sokféleségére és a talajállapot eltéréseire, jelenleg a termőhelyhez, talajhoz adaptált művelési rendszer alkalmazása látszik eredményesnek. Az időjárási szélsőségek fokozódása általában és adott termőhelyen is rangsorba állítja a lehetséges módszereket. A korábban jónak tartott megoldások, beleértve a szántást, ugyanis már egyre kevésbé biztonságosak.

A talajkímélő művelés iránti érdeklődés közel százhúsz évre tekint vissza Magyarországon. Sajátos, de az előrehaladás és a visszatartás tényezői a talajművelésben párhuzamosan jelentek meg az eltelt évek alatt. A művelési előrehaladást visszafogó tényezők között a sok évtized óta fennálló hiedelmek voltak a leginkább hátráltatók, mivel figyelmen kívül maradt a talajvédelem, továbbá a klímaváltozással kapcsolatos veszélyek enyhítésének igénye. Az előrehaladást a talajvédelem felvállalása, a gazdálkodási színvonal emelésének esélye és a klímakár csökkentés kényszere mozdította elő. Az előrehaladást alátámasztó tényezők között legfontosabbak a talajállapot tartós javulása és a klíma eredetű károk enyhítése, továbbá a termés biztonság megtartása és javulása.

Open access

Abstract

This paper presents an experimental study of abrasive waterjet turning of an extrusion aluminum alloy (AlMg0,7Si). The aim of the paper is to determine differences of two methods from the point of view of machined surface quality and the depth of penetration, i.e., the diameter of the parts after the turning process. During the experiments, the traverse speed of the cutting head and the rotation of the turned parts were changed, other parameters, like pressure of the water, abrasive mass flow rate were kept constant. Diameter and some surface roughness parameters of the test parts were measured after the machining. On the base of experimental results, advantages, and disadvantages of two methods are explained in the paper.

Open access

Abstract

The ball and Plate (BaP) system is the typical example of the nonlinear dynamic system that is used in a wide range of engineering applications. So, many researchers in the control field are using the Bap system to check robust controllers under several points that challenge it, such as internal and external disturbances. Our manuscript proposed a position control intelligent technique with two directions (2D) for the BaP system by optimized multi Fuzzy Logic Controllers (FLC’s) with Chicken Swarm Optimization (CSO) for each one. The gains and rules of the FLC’s can tune based on the CSO. This proposal utilizes the ability of the FLC’s to observe the position of the ball. At our work, the BaP system that belonged to Control Laboratory/Systems and Control Engineering department is used for real-time proposal implementation. The results have been showing a very good percentage enhancement in settling time, rise time, and overshoot, of the X-axis and Y-axis, respectively.

Open access

Abstract

Many security vulnerabilities can be detected by static analysis. This paper is a case study and a performance comparison of four open-source static analysis tools and plugins (PMD, SpotBugs, Find Security Bugs, and SonarQube) on Java source code. Experiments have been conducted on the widely used Juliet Test Suite with respect to six selected weaknesses from the official Top 25 list of Common Weakness Enumeration. In this study, analysis metrics have been calculated for helping Java developers decide which tools can be used when checking their programs for security vulnerabilities. It turned out that particular weaknesses are best detected with particular tools.

Open access