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Biocides are widely used in everyday life, and accordingly, human exposure to them is inevitable. Especially, the inhalational exposure of humans to biocides and resultant respiratory toxicity are gaining public interest due to the recent catastrophe associated with humidifier disinfectants. Aerosolized chemicals are subject to gravitational deposition and chemical degradation. Therefore, the characterization of the disposition of aerosols is essential to estimate the inhalational exposure to biocides. Here, we compared the disposition of aerosols of one of the commonly used biocide classes, isothiazolinone-based biocides, BIT, MIT, and OIT. An acrylic chamber (40 cm × 40 cm × 50 cm) was created to simulate the indoor environment, and a vacuum pump was used to create airflow (1 LPM). Biocides were sprayed from a vertical nebulizer placed on the ceiling of the chamber, and the distribution of particle sizes and volume was measured using the Optical Particle Sizer (OPS) 3330 device. During and after the aerosol spraying, airborne biocides and those deposited on the surface of the chamber were sampled to measure the deposition using LC-MS/MS. As a result, the broad particle size distribution was observed ranging from 0.3 to 8 μm during the nebulization. The inhalable particle faction (>2 μm) of the isothiazolinones was 32–67.9% in number but 1.2 to 6.4% in volume. Most of the aerosolized biocides were deposited on the chamber’s surface while only a minimal portion was airborne (

This study presents the unified high-fidelity flight dynamic modeling technique for compound aircraft. The existing flight dynamic modeling technique is absolutely depended on the experimental data measured by wind tunnel. It means that the existing flight dynamic model cannot be used for analyzing a new configuration aircraft. The flight dynamic modeling has to be implemented when a performance analysis has to be performed for new type aircraft. This technique is not effective for analyzing the performance of the new configuration aircraft because the shapes of compound aircraft are very various. The unified high-fidelity flight dynamic modeling technique is developed in this study to overcome the limitation of the existing modeling technique. First, the unified rotor and wing models are developed to calculate the aerodynamic forces generated by rotors and wings. The revolutions per minute (RPM) and pitch change with rotation direction are addressed by rotor models. The unified wing model calculates the induced velocity by using the vortex lattice method (VLM) and the Biot–Savart law. The aerodynamic forces and moments for wings and rotors are computed by strip theory in each model. Second, the performance analysis such as propeller performance and trim for compound aircraft is implemented to check the accuracy between the proposed modeling technique and the helicopter trim, linearization, and simulation (HETLAS) program which is validated. It is judged that this study raises the efficiency of aircraft performance analysis and the airworthiness evaluation.

Development of efficient surface passivation methods for semiconductor devices is crucial to counter the degradation in their electrical performance owing to scattering or trapping of carriers in the channels induced by molecular adsorption from the ambient environment. However, conventional dielectric deposition involves the formation of additional interfacial defects associated with broken covalent bonds, resulting in accidental electrostatic doping or enhanced hysteretic behavior. In this study, centimeter-scaled van der Waals passivation of transition metal dichalcogenides (TMDCs) is demonstrated by stacking hydrocarbon (HC) dielectrics onto MoSe

Pancreaticoduodenectomy (PD) is a standard surgical procedure for patients with periampullary cancer. During the follow-up period after PD, recurrence can be observed in various places with different prognosis. The aim of this study was to clarify the pattern of recurrence and factors affecting the survival of patients with periampullary cancer.Overall, 88 patients who received PD for distal common bile duct cancer or ampulla of Vater cancer were finally included and their clinical characteristics were analyzed. Patients were divided into three groups: recurrence-free (RF) group, an isolated locoregional recurrence (LR) group, and a distant metastasis (DM) group. Prognostic factors affecting recurrence in each group were analyzed and a survival analysis was performed.Perineural invasion (PNI), T stage, and lymphovascular invasion (LVI) were significant risk factors for LR and PNI, lymph node metastasis, LVI, and T stage were associated with DM group compared to RF group in univariate analysis, respectively. N stage and PNI were significant risk factors (T stage was a significant risk factor of LR, while PNI was a significant risk factor of DM. There was no significant difference in overall survival depending on the site of recurrence.

This study creates and combines the general maneuver libraries for fixed-wing aircraft to implement tactical maneuvers. First, the generalized maneuver libraries are established by analyzing the characteristics of tactical maneuvers required in battlefields. The 7th order polynomial is applied to both the creation of the maneuver libraries and the generation of the trajectories or flight paths for modal inputs. To track the desired trajectory, we design the Attitude Command Attitude Hold (ACAH) system and the Rate Command Rate Hold (RCRH) system using Model Following Controller (MFC). Moreover, the Line-of-Sight (LOS) guidance law is designed. In particular, the CONDUIT® is employed to optimize the gains so that the control systems meet the aircraft Handling Qualities (HQ) criteria. Finally, flight simulations are performed for the longitudinal loop, immelmann-turn, and climb-slalom-descent maneuvers to verify that tactical aggressive maneuvers are realizable via the combination of maneuver libraries. This study can contribute to the development of flight techniques for aircraft tactical maneuvers and to the revision of air force operational manuals. Keywords: 7th order polynomial, Attitude command attitude hold system, Handling qualities, Maneuver libraries, Rate command rate hold system, Tactical maneuvers

This paper intends to propose new inverse simulation techniques to cope with the numerical stability and accuracy problems frequently encountered with the integration inverse simulation methods widely used today. To achieve this, the pseudo-spectral method is adopted as a time integrator of the aircraft motion equations. In addition, the quasi-Newton and fixed-point iterative methods are applied to solve the resultant nonlinear algebraic equations in an efficient manner. These algorithms are integrated into a moving horizon framework to guarantee fast numerical convergence. The proposed methods are applied to the analyses of rotorcraft aggressive maneuvers such as popup, pirouette, and depart/abort mission-task-elements defined in the rotorcraft handling qualities requirements, ADS-33E-PRF. Numerical properties of the proposed methods are thoroughly investigated to clarify the effect of the numbers of quadrature nodes and time-horizon segments, and the level of maneuver aggressiveness on the robustness and efficiency of the analyses. Numerical efficiency and robustness of the present method are identified using specially designed performance measures such as the number of iterations to obtain a converged solution, functional residuals at the final solutions, and the variation of the adaptive relaxation factor. The results show that the present approach can provide extremely fast solutions of the inverse simulation problems and presents strong robustness to the level of maneuver aggressiveness, long-term simulation, and solution control parameters. Therefore, it is worthwhile to use the present techniques as one of the inverse simulation methods.

Biocides are commonly used as spray- or trigger-type formulations, thus dermal and respiratory exposure to biocide aerosol is unavoidable. However, little is known about the impact of aerosolization on the local toxicity of biocides on the skin or the airway. We compared the local toxicity of biocides after direct or aerosol exposure on reconstructed human skin epidermis and upper airway models. Three biocides, 1,2-benzisothiazol-3(2H)-one (BIT), 2-phenoxyethanol (PE), and 2-phenylphenol (OPP), most widely used in the market were selected. When the biocide was treated in aerosols, toxicity to the skin epidermis and upper airway tissue became significantly attenuated compared with the direct application as determined by the higher tissue viabilities. This was further confirmed in histological examination, wherein the tissue damages were less pronounced. LC-MS/MS and GC/MS analysis revealed that concentrations of biocides decreased during aerosolization. Importantly, the toxicity of biocides treated in 3 μm (median mass aerodynamic diameter (MMAD)) aerosols was stronger than that of 5 μm aerosol, suggesting that the aerosol particle size may affect biocide toxicity. Collectively, we demonstrated that aerosolization could affect the local toxicity of biocides on the skin epidermis and the upper airway.

This paper deals with the implementation techniques of an implicit integrator to achieve fast and accurate analyses of spacecraft dynamics. For this purpose, the pseudospectral method is adopted to directly integrate the second-order system of equations for both the spacecraft dynamics and corresponding state transition matrix. Various implementation techniques are proposed to enhance the numerical efficiency and integration accuracy, which include a moving horizon approach, the decoupled integration of the second-order dynamics for the state transition matrix, and the grid adaptation method. The numerical features of the proposed techniques are investigated through their applications to a spacecraft’s motion around highly eccentric elliptic orbits, and the resultant numerical errors and computing times are compared with those from the Runge-Kutta method to show the relative efficiency and accuracy of the presented methods. In addition, an optimal two-impulse orbit transfer from the Earth to the Moon is analyzed by implementing the proposed methods using a multiple-shooting framework. The results show that the proposed techniques are extremely effective for dynamical problems requiring intensive and accurate time integrations, and can provide much better accuracy and efficiency than the explicit Runge-Kutta integrator.

Vehicle-based applications were recently introduced to improve traffic safety and efficiency. These applications are classified into either safety-oriented or non-safety-oriented applications. Safety-oriented applications are typically provided by means of vehicle-to-vehicle (V2V) communications to support reliable and fast alert message propagation to all surrounding vehicles when an emergency occurs on the road. In vehicular ad-hoc network (VANET) broadcast-based packet forwarding is typically preferred for the propagation of urgent traffic-related information to all reachable nodes within a specified dangerous region. However, this approach may cause broadcast storm problems, which can lead to serious contention between transmissions from adjacent nodes. In this paper, we propose an alert message propagation scheme that is based on selective forwarding and aims to i) minimize the number of rebroadcasting nodes and ii) guarantee reliable and fast alert message delivery to all reachable nodes. Our scheme was evaluated using two different highway scenarios. The simulation results demonstrated that the performance of the proposed scheme was better than that of existing broadcast schemes in terms of the message delivery latency, the message delivery ratio, and the message rebroadcasting ratio.

Ad hoc wireless networks were considered to be the most suitable wireless communication system in order to support various applications in mobility environments. When providing real-time applications in ad hoc wireless networks, there are some requirements: i) the design of routing algorithm with packet delivery reliability while maintaining the established route for an arbitrary length of time (i.e., route duration); ii) the prompt transmission of the packets communication pairs (i.e., the source and destination) while minimizing packet delivery latency; iii) the minimization of the number of rebroadcasting nodes in route discovery procedure in order to suppress redundant routing overhead. In this paper, we analyze and compare packet forwarding approaches that have been proposed to alleviate network overhead problems and guarantee reliable and fast packet delivery to the destination in ad hoc wireless networks. Considering the discussion mentioned above, we conclude by highlighting opportunities for supporting multimedia application in ad hoc wireless networks with high mobility.

In MANETs, flooding-based route discovery is usually preferred in order to set up the route with reliability between transmission pair. However, this approach may cause a serious contention in transmission between adjacent nodes and a considerable amount of control packets. In addition, most of ad hoc routing protocols establish the route with minimum hop count. Consequently, the performance of ad hoc routing protocol is considerably affected by link (or route) duration since the network comprises the nodes with unrestricted mobility and constrained range in transmission. This paper proposes a novel routing algorithm that aims to i) minimize routing overhead in route discovery procedure, and ii) guarantee a reliable and fast packet delivery between source and destination, especially in providing real-time applications over MANETs. To achieve this objective, we introduce Relay Region within the transmission range of nodes in order to select optimal next relaying nodes for supporting specific application requirements in route discovery procedure. The proposed Relay Region is defined by the limited distance progress in transmission to next relaying node in order to maintain the established route for an arbitrary length of time (i.e., route duration) while meeting packet delivery reliability and delay constraints. The simulation results showed that the proposed scheme can significantly improve the performance of packet delivery ratio and packet delivery latency, reducing transmission redundancy in route discovery procedure.

Recently vehicular safety applications have been introduced to improve traffic safety and efficiency. These applications are classified into two types: safety-oriented and non-safety applications. In this classification, safety-oriented applications are usually provided by means of vehicular multi-hop broadcasting in order to support reliable and fast alert message propagation to all surrounding vehicles when an emergency event occurs on a road. In VANETs, broadcast-based packet forwarding is usually preferred in order to propagate urgent traffic-related information to all reachable nodes within a certain dangerous region. However, this approach may cause broadcast storm problem, which can lead to serious contention in transmission between adjacent nodes. With this motivation, in this paper, we propose an alert message propagation scheme based on selective forwarding that aims at i) minimizing the number of rebroadcasting nodes, and ii) guaranteeing reliable and fast alert message delivery to all reachable nodes. The proposed scheme is evaluated using two types of highway scenarios. The simulation results show that the proposed scheme performs better than existing broadcast schemes in terms of message delivery latency, message delivery ratio, and message rebroadcasting ratio.

Mobile ad hoc network consists of nodes with mobility thus resulting in frequent route breakage. Considering this problem, in this paper, we propose a novel routing algorithm which constrains the distance to next relay node to increase route life time in mobile ad hoc networks (MANET). By limiting the distance to next relay node, our algorithm lengthened route lifetime and enhanced the throughput. In the simulation part, we analyzed the impact of node speed and node density on the proposed algorithm and we used LAR for comparison. Simulation results showed that the proposed algorithm have a longer lifetime and higher throughput than LAR. However, our algorithm has a longer latency than LAR due to the increased hop count.

In this paper, the link maintenance probability that the two relay nodes in mobile ad hoc networks (Manet) communicates for a certain time was derived according to the initial distance between two relay node and speed of each node. Based on the link maintenance probability we further derived the route maintenance probability in multi hop Manet when the distance between source and destination node is given. Finally, we used Matlab to analyze the impact of distance between two adjacent relay nodes and communication time on link and route maintenance probability.

In wireless ad hoc networks, nodes compromise to forward packets for each other to communicate beyond their transmission range. Therefore, networks are vulnerable to wormhole attacks launched through compromised nodes because malicious nodes can easily participate in the networks. In wormhole attacks, one malicious node tunnels packets from its location to the other malicious node. Such wormhole attacks result in a false route with fewer. If source node chooses this fake route, malicious nodes have the option of delivering the packets or dropping them. It is difficult to detect wormhole attacks because malicious nodes impersonate legitimate nodes. Previous algorithms detecting a wormhole require special hardware or tight time synchronization. In this paper, we develop an effective method called wormhole attack prevention (WAP) without using specialized hardware. The WAP not only detects the fake route but also adopts preventive measures against action wormhole nodes from reappearing during the route discovery phase. Simulation results show that wormholes can be detected and isolated within the route discovery phase.

Intrusion detection systems are the basis of system protection from network attacks. However, intrusions are increasingly taking multi-stage procedures to attack a system, and cannot be detected by existing single stage intrusion detection systems. This paper proposes a multi-stage intrusion detection system architecture using hidden Markov model algorithm. This system considers every stage used by recent intrusions and applies them to the hidden Markov model algorithm to determine which intrusion is used in the audit data. This architecture reduces overheads of intrusion agents and raises efficiency of the whole system.

In ad hoc wireless network, the position-based routing scheme has been proposed for the purpose of reducing control signaling overhead in networks and establishing the shortest, multi-hop routing path. In spite of several benefits, however, there are still some problems such as connectivity, reliability and security in the process of route discovery. In this paper, we propose an enhanced next hop selection scheme to guarantee connectivity between intermediate nodes selected as next hop with the shortest, multi-hop path. In proposed scheme, we adopt a limited sending node's transmission range defined by Rc, alpha parameters to reduce the number of signaling packet and guarantee connectivity between two network nodes interconnected making up multi-hop routing path. Also, dc dwi parameters are suggested to select next hop making shortest path considering both sender and destination's aspect. Then, to support security, the safety table is newly defined by adding a specific subfield to a routing cache to identify the misbehaving nodes. To estimate the performance of the proposed scheme, we provide several simulation results comparing with exiting ones in terms of packet delivery ratio, end-to-end delay, and routing overhead.

Most Reliable Paths algorithm make it enable to select the most stable path on network by considering not only link cost but also link capacity, link operation probability and the size of message to be sent. But this algorithm uses a fixed value as link operation probability so that it can be applicable in the normal network state, not in the network state that traffic abnormally increase. To solve this problem, this thesis applies the packet drop probability of RED (Random Early Detection) method to the operation probability of the most reliable path algorithm so that the most reliable path can be guaranteed. For this purpose, we propose an All-Pairs Most Reliable Paths acquiring algorithm having time complexity thetas (n3) based on the All-Pairs Shortest Paths algorithm proposed by Floyd-Warshall.