Standard Mode Of Operation Research Articles

Crack resistance of reinforced-concrete sleepers with elastic rail fastening systems without base-plate

The article presents the main results of complex experimental and theoretical research into the crack resistance and the limit state of reinforced-concrete sleepers with elastic rail fastening systems without base-plate. The objective of this study is to uncover reasons for the cracks and other breakages during operation, demonstrate their importance, and produce a set of recommendations for prevention of the most serious defects. The research also involved statistical analysis of the defect factor for sleepers, and determined the number of defects by type according to track layout, traffic density, tonnage transported, concrete grade and other characteristics based on the results of full-scale research of track sections and surveys from maintenance specialists. The full-scale research was made on rail sections under standard operational modes and on a test track section of straight and curved elements with sleepers of concrete grades C32/40, C35/45 and C40/50.The study was based on numerical methods, modelling of the stress-strain behaviour of the track, and estimation of the performance of sleepers with cracks.The method used incremental-iterative algorithms to consider the elastic plastic properties of materials, solve contact problems in operation of rail fastening systems, and also reveal the structural nonlinearity of joint action for track elements. The method was realized in LIRA-SAPR software on the basis of Building Information Modelling (BIM) and the Finite Element Method (FEM).The results were verifiedby experimental research into the sleepers under static and dynamic loads with estimation of crack development in terms of concrete grades, deformation modulus, rigidities of the ballast layer and the sub-grade, position of the reinforcement and other characteristics.

Dissecting Energy Consumption of NB-IoT Devices Empirically

3GPP has recently introduced NB-IoT, a new mobile communication standard offering a robust and energy-efficient connectivity option to the rapidly expanding market of the Internet-of-Things (IoT) devices. To unleash its full potential, end devices are expected to work in a plug-and-play fashion, with zero or minimal configuration of parameters, still exhibiting excellent energy efficiency. We performed the most comprehensive set of empirical measurements with commercial IoT devices and different operators to date, quantifying the impact of several parameters to energy consumption. Our findings prove that parameters' settings do impact energy consumption, so proper configuration is necessary. We shed light on this aspect by first illustrating how the nominal standard operational modes map into real current consumption patterns of NB-IoT devices. Furthermore, we investigated which device-reported metadata metrics better reflected performance and implemented an algorithm to automatically identify device state in the current time-series logs. We worked with two major western European operators to provide a measurement-driven analysis of energy consumption and network performance of two popular NB-IoT boards under different parameter configurations. We observed that energy consumption is mostly affected by the paging interval in connected state, set by the base station. However, not all operators correctly implement such settings. Furthermore, under the default configuration, energy consumption in not strongly affected by packet size nor by signal quality, unless it is extremely bad. Our observations indicate that simple modifications to the default parameters' settings can yield great energy savings.

Negative‐sequence voltage elimination for distributed generators in grid‐feeding operation mode

A major concern of the power quality in distributed systems is related to the mitigation of voltage imbalances. This function can be implemented directly in the control system of the distributed generation power converters working simultaneously with the standard operation modes. This study presents a negative-sequence voltage elimination technique for distributed generators in grid-feeding operation mode. The proposal guarantees a complete elimination of the negative-sequence voltage, while operating without a priori in-depth knowledge of the grid configuration and its characteristics. The proposed control architecture is presented together with its pseudocode, a controller flowchart and a discussion of the implementation aspects. A closed-loop modelling is derived based on a complex transfer function approach, which is used to determine stability margins and control design guidelines. A laboratory setup was implemented to verify the performance of the proposed strategy.

Intermittent Injection for a Two-Stroke Direct Injection Engine

<div class="section abstract"><div class="htmlview paragraph">Cycle-to-cycle variation is one of the main factors for high fuel consumption and emissions of a two-stroke engine during the low-load and low-speed running. The increase of residual gas ratio due to the lower delivered amount of fresh scavenging air leads to a lower flame front speed and, therefore, to a slow combustion or even misfiring. The consequence is a very high level of unburnt hydrocarbons, since a large amount of fuel does not take part in the combustion process.</div><div class="htmlview paragraph">The use of a direct injection system allows a more flexible management of the injection of fuel over subsequent engine cycles. Under a low-load condition, the low request in terms of brake mean effective pressure (BMEP) can be achieved by performing a load control based on an intermittent injection, thus reducing the need for intake throttling and avoiding the loss of fresh fuel resulting from cycles without combustion. In more detail, the supply of fuel to the combustion chamber can be skipped for one or more cycles, thus performing a number of consecutive scavenging cycles with only fresh air. As a result, the fresh air is less diluted by the residual gas and the combustion efficiency increases.</div><div class="htmlview paragraph">This paper presents the results of a preliminary experimental activity on the use of an intermittent injection strategy with a Low Pressure Direct Injection (LPDI) system. In more detail, the effect of skipping one cycle - thus operating the two-stroke engine in a four-stroke-like mode - was investigated at part load conditions by considering four BMEP levels (i.e. from 1.0 bar to 2.5 bar). The benefits of such strategy were evaluated at the test bench and compared with the performance of the standard operation mode. In particular, the cycle-to-cycle variation was drastically reduced and the combustion misfire was avoided with the intermittent injection, thus leading to a strong reduction of both hydrocarbon emissions and brake specific fuel consumption.</div></div>

Extending the Battery Life of the ZigBee Routers and Coordinator by Modifying Their Mode of Operation.

Wireless sensor networks proliferate more and more in all social scopes and sectors. Such networks are implemented in smart homes, smart cities, security systems, medical resources, agriculture, automotive industry, etc. Communication devices and sensors of such networks are powered with batteries: the enlarging of battery life is a hot research topic. We focus on wireless sensor networks based on ZigBee technology. While sleep standard operation mode is defined for end devices, it is not the case for the rest of devices (routers and Coordinator), which usually always remain in active mode. We designed a formal optimization model for maximizing the enlarging of the battery life of routers and Coordinator, allowing us to delimit practical successful conditions. It was successfully tested with a standard ZigBee datasheet comprising technical data for sensors, routers, and coordinators. It was tested in a practical wireless sensor network assembly with XBee S2C devices. We derived, from the previous model, a novel but simple protocol of communication among routers and coordinators. It was tested in different use cases. We showed that when end devices generate traffic at regular intervals, the enlarging of the battery life of routers and Coordinator was possible only under certain use cases.

Unified call admission control in corporate domains

Call Admission Control is a central mechanism for assurance of quality of service in telephony. While CAC is integrated into Public Switched Telephony Network (PSTN), its application to voice over IP in a corporate environment is challenging not only due to the heterogeneity of technologies, but also because of the difficulty of implementation into commercial VoIP terminals or Access Points.We present a novel framework that unifies call admission control for VoIP telephony corporate users despite their access network (i.e., WiFi or Ethernet) under a single corporate management domain. Our Unified CAC (U-CAC) system can be implemented in a VoIP Gateway/Proxy and uses only standard protocols already present in commercial off-the-shelf devices, avoiding the need to modify the firmware of existing APs or VoIP terminals. We define two variants of the decision algorithm: basic and advanced. In the basic mode of operation, the admission of new calls is based on the availability of spare circuits and the impact of the new call in the speech quality of VoWiFi calls in progress. In the advanced mode of operation, the traffic load in affected APs is proactively reduced by reconfiguring ongoing calls before rejecting the new call. Simulation results show that the number of simultaneous VoWiFi calls under guaranteed quality increases with our unified call admission control scheme. When using the advanced mode of operation, the number of simultaneous calls under guaranteed quality can be doubled when compared to the standard mode of operation.

Performance Test of a Laboratory-Based Ambient Pressure X-ray Photoelectron Spectroscopy System at the Gwangju Institute of Science and Technology

The performance test of a laboratory based ambient pressure X-ray photoelectron spectroscopy (AP-XPS) system at the Gwangju Institute of Science and Technology (GIST) was carried out. The system, consisted of a Scienta R4000 HiPP-3 electron analyzer and a monochromatized Al Kα X-ray source, is designed to operate a gas pressure of up to 25 Torr. An Al polyimide X-ray window is used to isolate the X-ray source from the back-filled-type ambient pressure measurement chamber. Two modes of XPS operations were tested, a one-dimensional chemical imaging mode and a transmission mode. In the transmission mode, the lens voltage of analyzer was optimized for maximum detection of photo-excited electrons under elevated pressure condition, i.e., a typical standard lens operation mode. On the other hand, in the imaging mode, spatial information on the outgoing electrons is conserved to generate a one-dimensional chemical image of surface being measured. The test of the imaging mode on a Au/Si reference sample showed a spatial resolution of ∼10 µm under an Ar gas pressure of 500 mTorr. With the superb design of the differential pump and the electron transfer optics, a good signal-to-noise ratio was obtained for the XPS core-level spectra at Ar gas pressure up to 1 Torr.

A two centers study of postoperative adjuvant chemotherapy with S-1 versus SOX/XELOX regimens for gastric cancer after D2 resection: a cohort study.

Currently, radical surgery with D2 lymphadenectomy has become the standard operation mode of patients in East Asian countries who suffer from resectable gastric cancer. Our target is to compare the efficacy of postoperative adjuvant chemotherapy with S-1 versus SOX/XELOX regimens for gastric cancer after D2 resection. We selected 186 patients with gastric cancer who underwent D2 resection in Hangzhou First People's Hospital and Hangzhou Cancer Hospital from June 2014 to June 2017. All patients were followed up for more than 3years. The primary endpoint was disease-free survival (DFS), and the secondary endpoints were overall survival (OS) and toxicity. The 3-year DFS of monotherapy group and combined group were, respectively, 50.7% and 64.0%, while the 3-year OS were, respectively, 62.7% and 71.2%. The 3-year DFS and OS of the combined group were higher than the monotherapy group, but the differences had no statistical significance (3-year DFS: P = 0.071; 3-year OS: P = 0.224). Subgroup analysis showed that the DFS of patients with stage III gastric cancer in monotherapy group was significantly lower than the combined group, with the difference that had statistical significance (P = 0.030), while there was no significant difference in OS (P = 0.186). Most toxic and side effects seen in both groups had no significant differences, while the incidence of hand-foot syndrome and peripheral neurotoxicity in combined group was significantly higher than that in the monotherapy group (P < 0.001). For patients with advanced gastric cancer who underwent D2 resection, compared with S-1 regimen, there is prolonged disease-free survival trend with SOX/XELOX regimen, while there is no significant overall survival benefit.

Contending with Capitalism: Fatwas and Neoliberal Ideology

Neoliberal economic theorists posit that the economic sphere is to be differentiated from the social world and governed by its own rationality that is distinct from religious, ethical, social, or political considerations. My article explores how the issuance of fatwas in the contemporary Muslim world discursively compete with neoliberal capitalist ideology by embedding religious ethics in economic discourse. First, I contextualize this analysis with a historical discussion on how the Muslim world was incorporated into the capitalist world-system, a process that peripheralized their established economic and cultural practices. Then, I examine the contemporary fatwas on commercial transactions that are issued by an international Muslim organization. My overall argument is that the Islamic moral economy proposes financial arrangements that represent alternatives to capitalist financial practices, which are the standard modes of operation in global financial institutions. Such practices pose a challenge to Muslim economic ethics and law, a challenge that Muslims are trying to negotiate using traditional legal practices such as the fatwa.

Nanotribological Printing: A Nanoscale Additive Manufacturing Method.

Additive manufacturing methods are transforming the way components and devices are fabricated, which in turn is opening up completely new vistas for conceiving and designing products and engineered systems. Small-scale (submicrometer) additive manufacturing methods are largely in their infancy. While a number of methods exist, a particular challenge lies in finding methods that can produce a range of materials while obtaining sufficiently robust mechanical properties. In this paper, we describe a novel nanoscale additive manufacturing technique deemed "Nanotribological Printing" (NTP), which creates structures through tribomechanical and tribochemical surface interactions at the contact between a substrate and an atomic force microscope probe, where material pattern formation is driven by normal and shear contact stresses. The "ink" consists of nanoparticles or molecules dispersed in a carrier fluid surrounding the atomic force microscope (AFM) probe, which are entrained into the contact during sliding. Being stress-driven, patterning only occurs locally within regions which experience contact and sufficiently high stresses. Thus, imaging and measurement to characterize the morphology and properties of the deposited structures can be conducted in situ during the manufacturing process. Moreover, using local mechanical energy as the kinetic driver activating the solidification process, the method is compact and does not require application of a bias voltage or laser exposure and can be performed at ambient temperatures. We demonstrate (1) control of pattern dimensions with sub-100 nm lateral and sub-5 nm thickness control through variations in contact size and applied stress, (2) creation of amorphous, polycrystalline, and nanocomposite structures including sequential multimaterial deposition, and (3) formation of manufactured structures which exhibit mechanical properties approaching those of bulk counterparts. The ability to create nanoscale patterns using standard AFM cantilever probes and operation modes (contact mode scanning in fluid) with commercial AFM instruments, independent of substrate, establishes NTP as a versatile and easily accessible method for nanoscale additive manufacturing.

Hydraulic analysis of a GDI injector operation with close multi-injection strategies

The increase of injection pressure in GDI engines represents a proven development trend in the effort of limiting raw particulate emission, which is one of the most severe concerns for this kind of combustion system. Since increasing injection pressure level tends to cause significant issues in terms of spray penetration control, in parallel with ultra-high injection pressure multi-event strategies are being considered to improve the air-fuel mixture formation management. The adoption of these advanced injection strategies can potentially affect the injection system hydraulic behavior, hence an adequate control of each event fuel quantity is mandatory for a proper engine optimization.When the injector is operated according to a multi-event strategy, complex hydraulic and electro-magnetic phenomena may occur. Pressure waves triggered by each injection can eventually influence the subsequent events, modifying the injected volume compared to the expected, isolated event value. This hydraulic phenomenon is well-known for Diesel applications and is investigated in the present paper in a typical GDI configuration evidencing the effect of the dwell time value between consecutive events both in terms of injected volume and injection rate profile using a proprietary injection analyzer. Further, when consecutive injections are remarkably close, the succeeding injection event is likely to be influenced by a different, electro-magnetic phenomenon in addition to pressure waves propagation in the system pipes. With reduced dwell time strategies, the current profile driving the injector can be modified by a previous close-coupled actuation due to residual magnetization in the solenoid circuit. This phenomenon determines for the succeeding injection event a steeper transient of the solenoidal current, causing a faster injector needle rise and correspondingly a significantly increased injected quantity.In this paper, an innovative methodology is proposed to investigate in multi-injection strategies the effects of close injector actuations, evidencing the influence of hydraulic phenomena and of current profile modifications, respectively. The developed approach, named ETboost, consists in a double injection with a first dummy command. To this end, a short ETboost command is required not causing the injector needle opening and thus no triggering pressure waves that might influence the second injection. Using this analysis approach, the residual magnetization effects on a production GDI injector were experimentally investigated in terms of mean injected volume and instantaneous flow rate. The results obtained with reduced dwell-time were compared with the standard operation mode (single injection), evidencing a significant increment of the injected volume in particular in the ballistic operation where the actual injected quantity can be more than doubled if compared to standard actuation. The dependence of the injected volume on ETboost and dwell time was explored for different operating conditions, evidencing how reducing the dwell time and increasing the ETboost duration the injected volume is enlarged and the shot-to-shot dispersion is significantly reduced.

HARDWARE AND SOFTWARE ENGINE EMULATION IN THE AUTOPILOT SYSTEMS

Now a number of the leading firms work on creation of an automobile autopilot. The authors of the presented article offer to complement the system of an autopilot with the control system of the car technical condition. The developed hardware and software complex allows working with virtual mathematical model of the gas engine of the KamAZ truck and can be recustoized under different modifications of gas and diesel engines. At the same time by means of this complex there is an opportunity to reveal the latent defects of a control system and to reduce labor input of calibration procedures. The hardware and software allows testing electronic control units in standard and emergency operation modes of sensors and actuators, thereby providing compliance to the modern Russian and international requirements to control systems of cars.

Development of combined microstructure and structure characterization facility for in situ and operando studies at the Advanced Photon Source.

Following many years of evolutionary development, first at the National Synchrotron Light Source, Brookhaven National Laboratory, and then at the Advanced Photon Source (APS), Argonne National Laboratory, the APS ultrasmall-angle X-ray scattering (USAXS) facility has been transformed by several new developments. These comprise a conversion to higher-order crystal optics and higher X-ray energies as the standard operating mode, rapid fly scan measurements also as a standard operational mode, automated contiguous pinhole small-angle X-ray scattering (SAXS) measurements at intermediate scattering vectors, and associated rapid wide-angle X-ray scattering (WAXS) measurements for X-ray diffraction without disturbing the sample geometry. With each mode using the USAXS incident beam optics upstream of the sample, USAXS/SAXS/WAXS measurements can now be made within 5 min, allowing in situ and operando measurement capabilities with great flexibility under a wide range of sample conditions. These developments are described, together with examples of their application to investigate materials phenomena of technological importance. Developments of two novel USAXS applications, USAXSbased X-ray photon correlation spectroscopy and USAXS imaging, are also briefly reviewed.

Soft X-ray harmonic lasing self-seeded free electron laser at Pohang Accelerator Laboratory X-ray free electron laser

The demonstration of a harmonic lasing self-seeded free-electron laser (HLSS FEL) scheme in the soft X-ray range at the Pohang Accelerator Laboratory X-ray Free Electron Laser is presented. We report the experimental results of HLSS FEL radiation with the shortest wavelength of 1 nm by using the optimized phase shift of 2/3π. The key feature of the HLSS scheme is that the mode number is decreased (the longitudinal coherence length is enhanced) which is directly observed using a single-shot spectrometer. The spectral brightness is enhanced by a factor of 1.7 compared to the self-amplified spontaneous emission FEL because of the narrowed bandwidth. Our results show a good agreement with the theoretical expectation and simulations. The HLSS mode is a promising standard operation mode to generate a stable and high-brightness X-ray FEL that will provide more benefits to users for various applications.

Photon dose at the maze entrance door: The comparison of flattening filter and flattening filter free working modes

In recent years, field flattening free accelerators have been introduced in therapy practice. One of the objective of these measurements was to establish if the maze door, designed for accelerators operating with flattening filter can provide adequate shielding in field flattening free mode of operation. Linac installed in this standard one band maze vault is equipped to operate at 6 MV with field flattening filter and in field flattening free mode of operation. Series of measurements of the photon dose at the maze door (with different jaws openings and gantry positions) were performed in both operation modes with and without water canister to mimic standard therapy conditions. In this paper results of photon dose measurements, performed at the maze door of the therapy linear accelerator vault are presented in order to compare photon dose in flattening filter and flattening filter free operation modes. It was obtained that in field flattening free mode of operation, the dose at the maze door is always lower than the dose measured in standard mode of operation with the field flattening filter. In the case when FFF therapy practice should start in some existing therapy vault, no additional shielding measures need to be added at the existing maze door.

Method for the detection of small­sized air objects by observational radars

We proposed the introduction of an additional mode of dispersed reception and the combination of one-position and multiple reception of signals to the existing one-position observation radar. We improved the algorithm for detection of an air object at its irradiation by several transmitters. We provided compensation of a delay time and Doppler frequency in each receiving channel to a separate volume of an observation radar upgrading the algorithm. The improved algorithm for detection of an air object at its irradiation by several transmitters is reduced to: coherent processing of received signals in each processing channel in each element corresponding to the relevant separate volume and the relevant separate Doppler frequency; quadratic detection in each processing channel in each element corresponding to the relevant separate volume and the relevant separate Doppler frequency; weight summation of detector outputs for each processing channel in each element corresponding to the relevant separate volume and the relevant separate Doppler frequency. We constructed a structural diagram of the detector of an air object at its illumination by several transmitters. Each receiving channel of a signal is a multichannel for distance and speed. The diagram provides reception, coherent processing of echo signals from third-party sources, compensation of delay and Doppler frequency differences relative to a separate volume of the observation radar and incoherent weight summation. We carried out estimation of the efficiency of detection of an air object at its irradiation by several transmitters. We established that the transition from a single-channel detection of an air object to the detection of an air object at the incoherent combination of two channels results in a significant shift of detection characteristics to the left. We selected the number of receiving channels to be combined. We established that it is most effective to combine two, at most three, reception channels. We constructed a structural diagram of channels that process echo signals of an observation radar by combining the methods of one-position and differential signal reception. For combining of one-position and dispersed location modes of observation radars, we provided complexing of corresponding digital reception devices and digital signal processing systems. The main principle underlying the combination of the mentioned receiving devices is the informational supplement without violating the standard modes of operation of observation radar.

A decentralized strategy of structural reconfiguration in mitigation of vibrations

This contribution proposes a decentralized closed-loop control algorithm for semi-active mitigation of free vibrations in frame structures. The control uses dedicated dissipative devices, which consist of two controllable structural nodes placed pairwise in both ends of selected structural beams. The nodes are capable of a controlled transition between the standard frame mode of operation (full moment-bearing ability) and the truss mode in which they do not bear any moments and constitute in fact structural hinges. Syncronous switching is equivalent to reconfiguration of the global structure by (dis)allowing the involved beams to transmit moments and to accumulate vibration energy in the form of their bending strain. Upon switching to the truss mode, the accumulated energy is released into high-frequency local vibrations, which undergo quick dissipation by standard mechanisms of material damping. The approach is illustrated in a numerical example and verified in a preliminary experimental test.

Multi-Sensor Data Fusion for a Tethered Unmanned Helicopter Using a Square-Root Unscented Kalman Filter

The use of tethered Unmanned Aircraft Systems (UAS) in aerial robotic applications is a relatively unexplored research field. This work addresses the attitude and position estimation of a small-size unmanned helicopter tethered to a moving platform using a multi-sensor data fusion algorithm based on a numerically efficient sigma-point Kalman filter implementation. For that purpose, the state prediction is performed using a kinematic process model driven by measurements of the inertial sensors (accelerometer and gyroscope) onboard the helicopter and the subsequent correction is done using information from additional sensors like magnetometer, barometric altimeter, LIDAR altimeter and magnetic encoders measuring the tether orientation relative to the helicopter. Assuming the tether is kept taut by an actuated device on the platform during the system operation, the helicopter position is estimated relative to the anchor point. Although this configuration avoids the need of a GPS, a standard operation mode for estimation of the absolute position (the position relative to the inertial reference frame) incorporating corrections with the GPS position and velocity measurements, is also implemented in order to highlight the benefits of the proposed tethered setup. The filter performance is evaluated in simulations.

Magnetic measurements with atomic-plane resolution.

Rapid development of magnetic nanotechnologies calls for experimental techniques capable of providing magnetic information with subnanometre spatial resolution. Available probes of magnetism either detect only surface properties, such as spin-polarized scanning tunnelling microscopy, magnetic force microscopy or spin-polarized low-energy electron microscopy, or they are bulk probes with limited spatial resolution or quantitativeness, such as X-ray magnetic circular dichroism or classical electron magnetic circular dichroism (EMCD). Atomic resolution EMCD methods have been proposed, although not yet experimentally realized. Here, we demonstrate an EMCD technique with an atomic size electron probe utilizing a probe-corrected scanning transmission electron microscope in its standard operation mode. The crucial element of the method is a ramp in the phase of the electron beam wavefunction, introduced by a controlled beam displacement. We detect EMCD signals with atomic-plane resolution, thereby bringing near-atomic resolution magnetic circular dichroism spectroscopy to hundreds of laboratories worldwide.

Analyzing the Performance of the Advanced Encryption Standard Block Cipher Modes of Operation: Highlighting the National Institute of Standards and Technology Recommendations

When using a symmetric encryption algorithm, specifically the AES, the Block Cipher Mode of Operation to be used must be specified. Usually choosing the mode of operation is influenced by two main factors: 1. Security; and the 2. Performance of the mode. Most of the related literature explores the security of the modes. In contrast, this research paper explores, compares and evaluates the performance of the five modes of operation recommended by the National Institute of Standards and Technology (NIST). A code using Crypto++ cryptographic library has been developed to benchmark the performance of these modes. Based on the conducted experiments and obtained results, the Counter mode of operation has been found generally superior to the other four modes of operation in terms of performance especially when increasing the input size.