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The history of science and mechanics is confronted by two interconnected problems: a critical accumulation and systematization of historical information about the subject of study, and the relationship between events and the laws of their development.The influence of natural philosophy in classical times that led to the development of mechanics and engineering as a science from the 5th century B.C. to the Middle-Ages was investigated in a previous article by the author. The rapid development of mechanics as a science started in the 16th and the 17th century. Machine design as an applied science was heavily relying on mechanics. Since the beginning of the 19th century, mechanics became the theoretical basis of an increasing number of applied technical disciplines directly connected with the development of industry, the elaboration of new technological processes machines, and industrial plants. A brief history of the development of the theory of machines and mechanisms is attempted here, along with the personalities and Academic Institutions that influenced Mechanisms and Machine Theory from Medieval Times to the recent past.

Liquefied petroleum gas (LPG) cylinders are designed as thin-wall pressure vessels consisting of a cylindrical body and two almost hemispherical bottoms made of low carbon steel and welded together. LPG cylinders design, manufacturing, inspection and testing follow specific rules, Norms and Regulations. Pressure vessel design theory along with National Regulations and Product Specifications in force provide the initial design parameters and safety margin assumptions. A serious accident occurred on April 2, 2015 at Loutron village, close to the city of Amfilochia, in western Greece, explosion of an LPG bottle at a local restaurant. Five fatalities were reported at the time of the accident and three more injured were pronounced dead some months later. The accident gained extended publicity from the media arising concerns about safety in LPG distribution and operation. The local police requested an expert’s appraisement from the Mechanical Engineering and Aeronautics Department of the University of Patras, for the evaluation of the accident’s contributing factors. The accident investigated was a «boiling liquid expanding vapour explosion», and revealed potential threats from the operation of aged LPG bottles, and marginal inspection and testing procedures followed. A detailed analysis of the LPG cylinder operational characteristics along with a systematic design approach, fatigue, and failure analysis is presented here. The legislation in force, Regulations and Norms are also reviewed.

Development of logic into a science served as an instrument for the progress in natural philosophy and the scientific method in the 6th and 5th Centuries BC in China, India, and the Arabian world, the Middle East, the Ancient Greece and Rome. Rapid advancements in natural sciences were followed by systematic attempts to organize knowledge in the 4th to 1st Centuries BC in the Greek and the Hellenistic world, reaching maturity in the Roman Empire after the 2nd Century AD. Parallel development of philosophy, science and technology can be traced in the East too. The essentially random growth of machines and mechanisms driven by the pressure of necessity was followed by the development of complicated machines using design rules and concepts in a systematic way, and not arrived at empirically through a process of long evolution, were investigated very early in history. The influence of natural philosophy in classical times to the development of mechanics and engineering as a science from the 5th century B.C. to the Middle-Ages is discussed here.

Doureios Hippos or the Trojan Horse was the huge wooden structure, built by the Achaeans on Odysseus' suggestion, hiding a number of fully armed warriors inside, that eventually ended the ten year long siege of Troy (1194–1184 BC). The Greeks, pretending to depart and give up siege, left it before the city walls as an offering to the gods. The Trojan Horse was eventually moved inside the city walls, at night the hidden men emerged and opened the gates, thus permitting the Greek army to enter Troy and conquer it. From the references in the Iliad and vase paintings, archeological evidence concerning the Troy siege, and the Homeric shipbuilding, a reconstruction is attempted herewith. Analytical and numerical methods were incorporated to analyze the most conceivable loading situations of crucial structural elements of the reconstructed horse, load balancing, and transport kinematics and dynamics.

A new K-wire gripping configuration of the Ilizarov wire tensioning and hold assembly with an integrated load-cell is presented here. The method addresses two critical issues that appear in K-wire clamping assemblies in use, slippage and re-tensioning, being the major shortcomings of the standard fixation methods. The new grip can be re-tensioned by the patient, according to the load-cell measurements and the physician's instructions. The new design provides the advantages of a more accurate axial alignment of the K-wires, limited prestress loss, and lack of slippage. Detailed design with a commercially available solid modeling software and spread-sheet computation capability offers design flexibility for custom made solutions to adapt different patient's needs.

The intervention of a divinity in the action of a drama to resolve a conflict and, often, to bring the action to a conclusion was accomplished with ancient stagecraft, in which an actor playing the deity would be physically lowered by an elaborate piece of equipment into the stage area. This “god from the machine” was literally a Deus-Ex-Machina. Detailed information on stage scenery and machinery in the ancient theater are given by Vitruvius (1st Century BC) and Pollux (3rd Century AD). From the numerous references to such machines in extant tragedies or comedies and vase paintings, information about its design and operation is available, and efforts to reconstruct such mechanisms have been reported in the literature. Based on archeological evidence from the theater of Dionysus Eleuthereus in the western slope of the hill of the Acropolis, and previous reconstruction efforts, a new reconstruction attempt of the mechanism is presented. Analytical and numerical methods were incorporated to analyze the most conceivable loading situations of the different structural elements of the mechanism, as well as kinematics and dynamics, along with theater reconstruction.

Since ancient times upright stone slabs or pillars, the steles, bearing an inscription or design were serving as monuments or markers. Today, digital information and communications technologies produced a wide range of applications for collecting and processing historical data, and creating interactive information systems. This paper describes the design of a rotating info-stele providing on-screen visual and audio documentation for objects and monuments located through an integrated viewfinder. The info-stele is suitable either for indoor operation in museums or outdoors in archaeological sites. Initial design requirements incorporated the need for a smooth integration with sites of historical and cultural heritage, rotation according to a touch-screen signal, automatic positioning to pre-defined locations of interest, a silent two-speed operation mechanism for consecutive stops and all-the-way travel, user safety, and five or more language narrative options. The design objectives were followed by a detailed design procedure along with aesthetic considerations, user safety, strength and adverse environmental conditions resistance, vandalism proof design, and low maintenance. The proposed design is suitable for different applications as well as distant operation through the internet. The project was supported from the Greek Ministry of Culture.

Archimedes (ca. 287–212 BC) was born in Syracuse, in the Greek colony of Sicily. He studied mathematics probably at the Museum in Alexandria and made important contributions to the field of mathematics. Archimedes discovered fundamental theorems concerning the centre of gravity of plane geometric shapes and solids. He is the founder of statics and of hydrostatics. Archimedes was both a great engineer and a great inventor, his machines fascinated subsequent writers, and he earned the honorary title “father of experimental science”. Archimedes systematized the design of simple machines and the study of their functions and developed a rigorous theory of levers and the kinematics of the screw. His works contain a set of concrete principles upon which mechanics and engineering could be developed as a science using mathematics and reason.

Repeated loading of the outer strut leg of the Bjork–Shiley 60° convexo-concave (BSCC) valve results in fatigue crack propagation, with a duration from a few months to a few years. Sound and vibration analysis emitted from the strut of the BSCC valve due to impact is used to monitor the propagation of the fatigue crack before it would lead to the failure of one or both legs of the outlet strut. Analytical and experimental results established that the range of the fundamental natural frequency is 4000–8000 Hz. Analysis of sound emitted from the strut of the valve due to impact may be used to monitor the propagation of the fatigue crack before it would lead to the failure of the one or both legs of the outlet strut.

The development of transportation systems has significantly enhanced the welfare and modernization of society. Wooden vehicles pulled by animals have been used for land transportation since the early Bronze Age. Whole-body gharries with rigid wheels pulled by oxen appeared in Crete by 2000 BC or earlier. Horses originating from the East were depicted in early Cretan seal-rings of the same period. The two-wheeled horsedrawn chariot was one of the most important inventions in history. This vehicle provided humanity its first concept of personal transport and was the key technology of war for 2000 years. Chariots of Mycenaean and Archaic Greece with light and flexible four-spoked wheels acting as spring suspensions were depicted in vase paintings. The development of this vehicle incorporated the seeds of a primitive design activity and was important for engineering. The Trojan horse since 1194 BC and the helepolis since 700 BC were the first known machines on a wheeled base transported by horses or self-powered. Ancient engineers invented bearings lubricated with fat, and Romans introduced the ancestors of ball bearings for their wagons and carts. The historic evolution of wheeled transportation systems, along with early traction, suspension, and braking systems, is presented in this paper. Analytical and numerical methods are incorporated to analyze the most conceivable loading situations of typically reconstructed wheeled transportation systems in ancient times. Traction requirements both for horse-driven machines and the power for internal motors are also analyzed. This study can serve as a basis for further development of detailed reconstruction of transportation systems in antiquity.

The rollover stability of tank vehicles depends on a number of factors that result in a lateral shift of the centre of gravity, which influences roll dynamics in cornering. The most important factors are the height of the centre of gravity, the track width, the axle roll stiffness, suspension and tyre compliance, and suspension roll stiffness. A tilt table test and, alternatively, a calculation method are suggested for implementation by United Nations Economic Commission for Europe (UNECE) Regulation 111. In Greece, no available approved testing rig is available to carry out the required tests for the conformity of those vehicles with Regulation 111 and, consequently, the calculation method is almost exclusively adopted. However, the calculation method for Regulation 111 still remains a theoretical way to check the vehicle behaviour owing to the large number of non-validated physical parameters involved. Thus, there is a lack of reliability between results obtained by the calculation method from different inspection bodies for similar vehicles. A combined experimental and calculation method that determines the overall torsion-angular displacement relation for a vehicle on an inclined level under its own weight is discussed, and results of the application of this method in a large series of various types of road tanker are presented in this paper.

The grind-hardening process is based on the utilization of the generated heat in the grinding zone for inducing a metallurgical transformation on the surface of the ground workpiece. The workpiece surface is locally heated above the austenitization temperature and subsequently is quenched to increase surface hardness. A theoretical model was developed for the prediction of the heat-generation rate as a function of the process parameters and the grinding wheel characteristics. The model combined with a database of relationships among the heat entering the workpiece, the process parameters, and the hardness penetration depth (HPD), which was presented by the authors in an earlier publication, allows the assessment of the grinding wheel’s effect characteristics on the hardening output of the process. The experimental results have verified the predictions of the theoretical model and served for its calibration.

The torsional vibration of a circumferentially cracked cylindrical shaft is studied through an “exact” analytical solution and a numerical finite element (FE) analysis. The Hu–Washizu–Barr variational formulation is used to develop the differential equation and the boundary conditions of the cracked rod. The equations of motion for a uniform cracked rod in torsional vibration are derived and solved, and the Rayleigh quotient is used to further approximate the natural frequencies of the cracked rod. Results for the problem of the torsional vibration of a cylindrical shaft with a peripheral crack are provided through an analytical solution based on variational formulation to derive the equation of motion and a numerical analysis utilizing a parametric three-dimensional (3D) solid FE model of the cracked rod. The crack is modelled as a continuous flexibility based on fracture mechanics principles. The variational formulation results are compared with the FE alternative. The sensitivity of the FE discretization with respect to the analytical results is assessed.

A linear full-car model with seven degrees of freedom was adopted for the simulation of the dynamic behavior of road tankers with a fixed tank. The vehicle is subject to selected typical road surface profiles and inertial loads due to acceleration, braking and driving on a curve. For the simulation, a Monte Carlo method is used for a sensitivity analysis of the suspension characteristics including tires and the road tanker’s CG vertical shift due to the liquid load in relation with the vehicles response to road profile. A standard deviation was assumed for the aforementioned vehicle design characteristics introduced for the simulations performed. The road tanker’s dynamic response was investigated and furthermore results were compared with a static model as proposed by UN-ECE Regulation R-111 for lateral stability. The proposed method can be used as a design tool for the prediction of road-tankers dynamic response and roll-over threshold from an early design stage.

The presence of a crack in a structural member introduces a local flexibility that affects its dynamic response. Moreover, the crack will open and close in time depending on the loading conditions and vibration amplitude. The changes in dynamic characteristics can be measured and lead to an identification of the structural changes which eventually might lead to the detection of a structural flaw. The results of various independent evaluations of changes in the natural frequency of vibrations of cracked structural elements are reported. A crack model of a continuous flexibility, found with fracture mechanics methods using the displacement field in the vicinity of the crack developed recently is used here. The analytical results for the cracked elements behaviour based on the continuous crack flexibility vibration theory were correlated with numerical solutions, the lumped-crack beam vibration analysis and experimental results obtained on aluminium and steel beams with open cracks.

This memorial tribute to the late Professor Andrew D. Dimarogonas is in two parts. The first part is a brief account of his life and his professional career and achievements. The second part is a bibliography of his publications.

When a material is subjected to an alternating stress field there are temperature fluctuations throughout its volume due to thermoelastic effect. The resulting irreversible heat conduction leads to entropy production, which in turn is the cause for thermodynamic damping. An analytical investigation of the entropy produced during a vibration cycle due to the reciprocity of temperature rise and strain yielded the change of the material damping factor as a function of shape and magnitude of existing crack in the structure. A homogeneous, isotropic, elastic bar of orthogonal shape is considered with a single-edge crack under alternating uniform axial stress. The analytical determination of the dynamic characteristics of the cracked structure yielded the damping factor of the bar, the material damping factor and a good correlation of depth of crack with the damping factor. Experimental results on cracked bars are in good correlation with the analysis.

A continuous cracked beam vibration theory is used for the prediction of changes in transverse vibration of a simply supported beam with a breathing crack. The equation of motion and the boundary conditions of the cracked beam considered as a one-dimensional continuum were used. The eigenfrequency changes due to a breathing edge-crack are shown to depend on the bi-linear character of the system. The associated linear problems are solved over their respective domains of definition and the solutions are matched through the initial conditions. The changes in vibration frequencies for a fatigue-breathing crack are smaller than the ones caused by open cracks. The method has been tested for the evaluation of the lowest natural frequency of lateral vibration for beams with a single-edge breathing crack. Experimental results from aluminium beams with fatigue cracks are used for comparison with the analytical results.

The dynamics of a cracked fixed-free bar with a breathing crack in longitudinal vibration is investigated. The Hu–Washizu–Barr variational formulation was used to develop the equation of motion and the boundary conditions of the cracked bar as a one-dimensional continuum. The crack was modelled as a continuous flexibility using the displacement field in the vicinity of the crack found with fracture mechanics methods. The eigenfrequency changes due to a single open-edge breathing crack, are shown to depend on the bilinear character of the system. The associated linear problems are solved over their respective domain of definition and then the solutions are matched through the initial conditions. These changes are smaller than the ones caused by open cracks. The method has been tested for different bar configurations corresponding to crack location, crack depths, cross-section dimensions, and Poisson’s ratio. The natural frequencies obtained from this model agree well with experimental results.

A continuous cracked bar vibration theory is developed for longitudinal vibration of rods with an edge crack. The Hu–Washizu–Barr variational formulation was used to develop the differential equation and the boundary conditions of the cracked bar as a one-dimensional continuum. The crack was modelled as a continuous flexibility using the displacement field in the vicinity of the crack found with fracture mechanics methods. The results of three independent evaluations of the lowest natural frequency of longitudinal vibrations of a bar with a single edge crack are presented: the continuous cracked bar vibration theory, the lumped crack bar vibration analysis, and experimental results obtained on aluminum bars with fatigue cracks. Experimental results fall between the values predicted by the two analytical methods. Moreover, the continuous bar theory agrees better with the experimental results than the lumped crack flexibility theory for small cracks. For larger cracks, a / h >0.4, experimentation was difficult due to the co-existence of several coupled modes and no reliable results could be obtained.

A continuous cracked beam vibration theory is developed for the lateral vibration of cracked Euler–Bernoulli beams with single-edge or double-edge open cracks. The Hu–Washizu–Barr variational formulation was used to develop the differential equation and the boundary conditions of the cracked beam as a one-dimensional continuum. The displacement field about the crack was used to modify the stress and displacement field throughout the bar. The crack was modelled as a continuous flexibility using the displacement field in the vicinity of the crack, found with fracture mechanics methods. The results of two independent evaluations of the lowest natural frequency of lateral vibrations for beams with a single-edge crack are presented: the continuous cracked beam vibration theory developed here, and a lumped cracked beam vibration analysis. Experimental results from aluminum beams with fatigue cracks are very close to the values predicted. A steel beam with a double-edge crack was also investigated with the above mentioned methods, and results compared well with existing experimental data.

A continuous cracked bar vibration model is developed for the lateral vibration of a cracked Euler-Bernoulli cantilevered beam with an edge crack. The Hu-Washizu-Barr variational formulation was used to develop the differential equation and the boundary conditions for the cracked beam as an one-dimensional continuum. The crack was modelled as a continuous flexibility using the displacement field in the vicinity of the crack found with fracture mechanics methods. The results of three independent evaluations of the lowest natural frequency of lateral vibrations of an aluminum cantilever beam with a single-edge crack are presented: the continuous cracked beam vibration model, the lumped crack model vibration analysis, and experimental results. Experimental results fall very close to the values predicted by the continuous crack formulation. Moreover, the continuous cracked beam theory agrees better with the experimental results than the lumped crack flexibility theory.

A consistent continuous cracked bar vibration theory is developed. The stress and displacement field about the crack was used to modify the stress and displacement field throughout the bar, and reduction to one spatial dimension was achieved by integrating the stress and displacement fields throughout the bar cross-sections so that the total displacement would be exact. The resulting linear differential equation with variable coefficients has the modified displacement field due to the crack imbedded in it. Any number of cracks can be introduced into the differential equation as modifications of the displacement field. A numerical solution and a first order perturbation solution are presented for the prediction of changes in longitudinal vibration natural frequencies of a fixed-free bar with a single open-edge transverse crack. To assess the validity of the assumptions made experiments on aluminium bars with fatigue cracks were performed. The analytical results correlate very closely with experimental results with better correlation than the local flexibility solution.

In Chap. 10 the Hu-Washizu-Barr variational formulation is used for the development of the differential equation and boundary conditions for a cracked rod. Based on the general variational principle and independent assumptions about displacement, momentum, strain and stress fields of the cracked rod with one or more pairs of transverse symmetrically disposed open edge cracks along its length, the equations of motion in torsional vibration were derived. Crack is introduced as a stress disturbance function, and stress field is determined by fracture mechanics methods. Strain energy density theory has been used for an accurate evaluation of the stress disturbance function. The strain energy density criterion is based on local density of the energy field in the crack tip region, and no special assumptions on the direction in which the energy released by the separating crack surfaces is required.

The question of crack detection from dynamic measurements is further extended and discussed in Chap. 7. A general stiffness matrix for cracked structural members is introduced, to model the respective dynamic system. This stiffness matrix can be further utilized for static, dynamic or stability analysis of a structure with cracked members of rectangular or circular cross-section. Off-diagonal terms indicate vibration coupling. The change in dynamic response is analytically evaluated for simple systems and by means of approximate methods for more complicated ones. The outlined procedure can be used for engineering analysis in two ways: (a) as a design tool, to assist in structural optimization with the objective of achieving certain specific dynamic characteristics; and (b) as a maintenance and inspection tool, to identify structural flaws, such as cracks, by linking the variations in service of the structure's natural frequencies to structural changes due to the cracks.

Chapter 4 deals with flow-induced vibration of rotors and in particular with the most important case, known as 'steam whirl', often appearing in large steam turbines. Stability criteria, Thomas Stability Criterion and Torque-Deflection Number are applied and compared. Vibration of rotors in fluid annuli occurs due to dynamic interaction of cylinders with the surrounding fluid in parallel or cross-flow. The integrated effect of pressure and dynamic fluid forces generated results to imbalance. Application of Hurwitz-Routh determinants is used for checking stability conditions. Self-excited vibration of a rotating hollow shaft partially filled with viscous liquid occurs within a certain range of rotating speed. Approximate solutions of the equations of motion for the non-dimensional time-dependent radial and circumferential velocity of a small internal liquid element yield non-dimensional liquid forces and, furthermore, stability limits for the rotor. The marginal condition under which the system becomes absolutely stable is investigated.

Approximate evaluation of rotors flexural eigenfrequencies is investigated in Chap. 1. However, the formulation is similar for torsional vibrations of shafts or even vibrations of elastic systems in general. The Dunkerley's rule for the determination of lowest eigenfrequency of a lumped-mass, multi-degree-of-freedom elastic shaft is applied along with its extension to higher modes. This procedure generally provides lower bounds for the eigenfrequencies, but its accuracy can be increased at will by means of the root-squaring process, as suggested by Graeffe and Lobachevsky, applicable both to undamped and damped systems. Extension to continuous systems is considered too, and an integral equation formulation of the eigenvalue problem, providing upper and lower bounds for the eigenvalues, which by means of an iterative process can be brought as close as desired. Those methods are useful for predicting bending and torsional fatigue life of rotors and shafts, and furthermore, for developing methodologies for damage detection, and the estimation of position and size of flaws and cracks in rotating machinery.

Chapter 3 presents the main mathematical models used in rotor dynamic analysis. The one disc-flexible rotor model, called Jeffcott or de Laval rotor, can be used to derive qualitative features, since it lends itself to analytical treatment. The transfer matrix is powerful to model very long and complex rotors but it is strictly limited to linear systems and has certain problems of numerical instability. Lumped mass systems lead to very tedious computations, compared with the transfer matrix method, but they can be used to describe nonlinear systems. For realistic rotor forms, a discrete finite element model is presented, applicable to very complicated rotor geometries, yet leading to a manageable system of equations for linear or non-linear analysis.

Packing rub effect is the unstable vibration induced by friction forces and generated heat on a rotor when it rubs on a clearance annulus. Its main controlling factors are friction characteristics at the sliding contact and the dynamic response of the rotor, bearings, supports and foundation system. In Chapter 5 rotor instabilities are investigated, resulting from friction heating, a phenomenon known as the 'Newkirk effect'. The interaction between vibration characteristics and heat generation leads to a non-linear feedback system exhibiting either stable or unstable behavior.

In Chap. 9, modeling and formulation of the governing dynamic equations for cracked Euler-Bernoulli beams in flexural vibration are studied. The results of three independent evaluations of the lowest natural frequency of lateral vibrations of beams with single-edge cracks and various end conditions are investigated: continuous cracked beam vibration theory, lumped crack flexibility model vibration analysis, a finite element method, and experimental results. For the case of torsional vibration of a shaft with a peripheral crack, the Hu-Washizu-Barr variational formulation is adopted for obtaining the differential equation of motion, with plausible assumptions about displacements, momentum, strain and stress fields, along with the associated boundary conditions. For the experimental procedure crack propagation and formation of stationary cracks is achieved by a vibration technique. Continuous cracked beam theory agrees better with experimental results than lumped crack theory.

The effects of variable elasticity in rotating machinery occur with a large variety of mechanical, electrical, etc., systems, in the present case, geometrical and/or mechanical problems. Parameters affecting elastic behavior do not remain constant, but vary as functions of time. Systems with variable elasticity are governed by differential equations with periodic coefficients of the Mathieu-Hill type and exhibit important stability problems. In this chapter, analytical tools for the treatment of this kind of equations are given, including the classical Floquet theory, a matrix method of solution, solution by transition into an equivalent integral equation and the BWK procedure. The present analysis is useful for the solution of actual rotor problems, as, for example, in case of a transversely cracked rotor subjected to reciprocating axial forces. Axial forces can be used to control large-amplitude flexural vibrations. Flexural vibration problems can be encountered under similar formulation.

Chapter 8 deals with the inverse problem of the one encountered in Chap. 5, e.g. the heat generated by torsional vibration of rotating shafts. The corresponding mechanisms are associated with internal damping and plastic deformation. Practically all the energy of 476 plastic deformation is transformed into heat. For elastic deformation part of the strain energy is transformed into heat, depending on material loss factor. This phenomenon has been identified as the cause of large-scale failures of power equipment, with electrical disturbances being the cause of rotor torsional vibration. Maximum temperatures given in the form of design nomograms can assist in estimating the overheating of shaft of rotating machinery, where such phenomena are present. A typical turbo-generator shaft is analyzed for vibrations occurring during electrical transients.

The problem of cracked rotor dynamics is discussed in Chap. 6. Analytical formulation for crack local flexibility in relation to crack depth yields a supervisory instrument which can give an early crack warning. Fracture mechanics methods provide stress intensity factors for the investigation of rotor’s dynamic performance for varying crack depth. Open cracks lead to linear systems, while closing cracks lead to non-linear ones. Analytical solutions are obtained, which can be used to monitor crack propagation or to identify cracks in service.

A tapered spring friction clamping assembly replaced the bolted grip and hold assembly of the Ilizarov wire tensioning device. An integrated force transducer records the wire tension and according to the physician’s instructions the patient adjusts himself the K-wire tension. Analytical solutions of the K-wires axial stress in relation with transverse loading provide the basis for the design of different gripping configurations to adapt different applications needs regarding K-wire length and diameter, varying tension force requirements, and different force transducers configurations. The proposed method provides design flexibility, and operational validation of this new Ilizarov fixator.

Greece, via its PRODEX membership intends to meaningfully participate to the instrument development of a flagship ESA mission, the Solar Orbiter (SolO). This involvement pertains to hardware development for SolO's Spectrometer/Telescope for Imaging X-rays (STIX), namely, STIX's movable attenuator. SolO will allow close-up and high-latitude studies of our mother star, the Sun, based mostly on remote-sensing measurements (imaging). STIX is a critical SolO instrument, enabling one of its major science goals: understanding and acceleration of electrons at the Sun and their transport into interplanetary space. The attenuator, or shutter, that will be developed by the Greek team, is a critical component of the STIX instrument. Attenuators are dictated by the substantial dynamical range of incident X-ray fluxes from solar flares: the largest X-ray flares can give as many as 105 more count rates in X-ray photons compared to those of the smallest microflare that STIX can detect. lt is proposed that two mechanisms are developed for a comparative study. First, a mechanism based on sensitive Shape Memory Alloy actuators and, second, one based on a piezoelectric actuator module. Both mechanisms will be designed and manufactured and then tested in vacuum and alternating high-low temperature conditions. Evaluation of reliability and accuracy in assembly and operation will follow. A vibrating table will be used for the dynamical analysis of the mechanism and independent strength tests of the various parts of the mechanism will follow.

Archimedes (ca. 287–212 BC) was born in Syracuse, in the Greek colony of Sicily. He studied mathematics probably at the Museum in Alexandria. Archimedes made important contributions to the field of mathematics. Archimedes discovered fundamental theorems concerning the center of gravity of plane geometric shapes and solids. He is the founder of statics and of hydrostatics. Archimedes was both a great engineer and a great inventor, his machines fascinated subsequent writers, and he earned the honorary title “father of experimental science”. Archimedes systematized the design of simple machines and the study of their functions and developed a rigorous theory of levers and the kinematics of the screw. His works contain a set of concrete principles upon which mechanics could be developed as a science using mathematics and reason. His contribution separates engineering science from technology and crafts, often confused for matters arrived at empirically through a process of long evolution. His works have influenced science and engineering from the Byzantine period to the Industrial Revolution and the New Era.

In some ancient Greek drama plays, the stage machine used to bring the gods or the heroes of the tragedy on stage, known with the Latin term deus-ex-machina, was used for the solution of an apparently insoluble crisis. A twin-facing stone base was found in the theater of Phlius in Corinthia, Greece, behind the stage building. The existence of similar foundations in other ancient theaters indicates their use for specific purposes connected with the needs of the play. An attempt to reconstruct the mechanism is presented based on archeological evidence and literary descriptions. The reconstructed mechanism was designed for path generation and comprised a single beam with ropes controlling its planar motion and a sidle twin lifting system. DOI: 10.1115/1.4000530

Developments in natural philosophy and the scientific method in the 6th and 5th Centuries BCled to rapid development of engineering design in the 4th to 1st Centuries BCin the Greek and Hellenistic world, reaching maturity in the Roman Empire after the 2nd Century ADwhen Greek mathematical works started being translated into Latin. Design rules and concepts were practiced extensively by the engineers of ancient times leading to machine design from machine elements to the design of a machine as a system. Purely mechanical treatises on machinery go back to the 4th century BC.For the solution of mechanical problems and the design of equipment many basic scientific principles had to be explained at this time, and also trial and experimentation was established. The process of engineering design evolution from the 4th century BCup to modern era is discussed here.

A computer-aided numerical method for the design of a cam-follower mechanism and NC milling for a planar cam profile is presented. The method consists of an iteration method for the calculation of the follower motion properties (oscillation, velocity and acceleration, jerk) using the vector differences for three successive points on the cam profile. With the aid of a CAD program the results of the method are exported to the NC milling machine, thus facilitating the programming procedure and leading to a significant reduction of the NC code size. Numerical examples have been reported to compare differences of the proposed method versus the analytical design parameters of the cam-follower mechanism.

The stage machine used to bring the gods or the heroes of the tragedy on stage, known with the Latin term Deus ex machina was used in some ancient Greek drama, for the solution of an apparently insoluble crisis. This intervention of a god or a hero brought on stage was possible by this elaborate piece of equipment, the mechane. Archaeological evidence in the ancient Greek theatre of Phlius (Corinthia) was reappraised in an attempt to reconstruct the mechane.

Archimedes (ca. 287–212 BC) was born in Syracuse, in the Greek colony of Sicily. He studied mathematics at the Museum in Alexandria. He is the founder of statics and of hydrostatics, Archimedes discovered fundamental theorems concerning the center of gravity of plane geometric shapes and solids and his machine designs fascinated subsequent writers. Archimedes systematized the design of simple machines and the study of their functions and developed a rigorous theory of levers and the kinematics of the screw. His works contain a set of concrete principles upon which design can be developed as a science using mathematics and reason.

Ten thousand domestic hot water solar systems were surveyed in Greece to assess component and system reliability. Data concerning the functioning condition of the systems was collected, a computerized data base was established and statistical analysis was performed. This work is part of a solar system evaluation program within the European Community. Greece was selected due to the high concentration of solar collector systems and the fact that these systems have reached maturity, the average lifespan being five years.

In some ancient Greek drama, an apparently insoluble crisis was solved by the intervention of a god often brought on stage by an elaborate piece of equipment. This “god from the machine” was literally a Deus Ex Machina. Archaeological evidences and descriptions of mechanisms used in the ancient Greek theatre were investigated in an attempt to reconstruct the Deus Ex Machina. None of these machines, made of perishable materials is extant. However, from the numerous references to such machines in extant tragedies or comedies and vase paintings, information about its design and operation is available. Static and dynamic analysis and simulation of the mechanism kinematics were performed. The reconstructed mechanism is a spatial three or four bar linkage designed for path generation.

Archimedes (ca. 287–212 BC) was born in Syracuse, in the Greek colony of Sicily. He studied mathematics at the Museum in Alexandria. Archimedes systematized the design of simple machines and the study of their functions. He was probably the inventor of the compound pulley and developed a rigorous theory of levers and the kinematics of the screw. He is the founder of statics and of hydrostatics, and his machine designs fascinated subsequent writers. Archimedes was both a great engineer and a great inventor, but his books concentrated on applied mathematics and mechanics and rigorous mathematical proofs. Archimedes was also known as an outstanding astronomer; his observations of solstices were used by other astronomers of the era.

The objective of this work is to develop a fault diagnostic system of an electric car based on artificial neural networks (ANN). Data from an on-board data acquisition system capable of measuring a number of parameters during the electric car operation are used to train an artificial neural network. The car’s monitoring system using the computational power of modern portable personal computers, user-friendly data input and output, and fullscreen editor capabilities is used for fault diagnosis. The ANN was trained to predict the temperature of the two motors of the electric car in order to detect any fault. The training data were learned by the ANN with an excellent accuracy. The results obtained for the training set are such that they yield coefficients of multiple determination (R2-values) equal to 0.9912 and 0.9939 corresponding to the values of the temperatures of the two motors respectively. Completely unknown data were then used for validation of the network. The correlation coefficients obtained in this case were equal to 0.954 and 0.987 for the temperature of the two motors respectively, which are very satisfactory. The fault diagnostic system developed compares the measured and predicted temperatures from the two motors and gives an “error” when a difference greater than a user defined tolerance is obtained. A polling routine was developed which sums-up the error signals and only gives a “fault” when 10 consecutive error reading are recorded. In this way false error conditions, which might arise from erroneous data recorded from the thermocouples and/or from wrong predictions of the network, are avoided

An expert system capable of learning from the electric car operation is used to evaluate the drive train performance and energy management and furthermore, monitor faults. This system using the computational power of modern portable personal computers, user-friendly data input and output, and full-screen editor capabilities is used for on-board drive train monitoring, energy management optimization, and fault diagnosis.