Showing papers by "Saab AB published in 2015"

Forming induced wrinkling of composite laminates with mixed ply material properties; an experimental study

Abstract: One disadvantage of multi-layer forming of unidirectional (UD) prepreg tape is the risk of out-of-plane wrinkling. This study aims to show how mixed ply material properties affect global wrinkling ...

Measurement of radio signal propagation through window panes and energy saving windows

Abstract: Glass windows have undergone an energy saving evolution over the past three, four decades, from single panes till today's ultralow-emission windows. While the earliest energy saving windows were constructed as a sandwich of clear glass panes using the vacuum-flask principle, modern low-emission windows includes panes with coatings of metal and/or metal oxides. This coating has caused radio propagation problems for communication systems; something that may be utilized to protect a building from intentional electromagnetic interference (IEMI) attacks and to help protecting against information leakage. In this paper measurements of the shielding performance of different generations of windows and qualities of window panes are presented. The intention is to include the results in a guide-line for IEMI protection of critical infrastructures. Measurements are made using two complementary methods; in a nested reverberation chamber and in a semi-anechoic chamber, both over the range 1 – 18 GHz. The results show a clear generation dependency where the energy saving windows largely do not attenuate RF signals at all and low-emission windows offer shielding effectiveness values between 10 and 45 dB with potentially as much as around 60 dB in the upper half of the spectrum.

A fluid actuator arrangement

Abstract: The present invention regards a fluid actuator arrangement comprising a first cylinder (3, 3') and a first piston body (5, 5') symmetrically arranged along a longitudinal axis (X), wherein the first cylinder (3, 3') exhibits a cylindrical inner peripheral surface (7), a first end (9, 10) and a second end (11, 12) forming a first cylinder interior (13); the first piston body (5, 5') comprises a first portion (21, 21') and second portion (23, 23') and a radially protruding portion (15) therebetween,the radially protruding portion (15) is slidingly arranged in the first cylinder interior (13) and protrudes outwardly towards the cylindrical inner peripheral surface (7) dividing the first cylinder interior (13) into a first cylinder chamber (17) and a second cylinder chamber (19) The first portion (21, 21')of the first piston body (5, 5´) sealingly extends through a first opening (25) of the first end (9) and the second portion (23, 23')of the first piston body (5, 5´) sealingly extends through a second opening (27) of the second end (11);and the first portion (21, 21') of the first piston body (5, 5') exhibits a larger diameter than the second portion (23, 23') of the first piston body (5, 5') and comprises an open cavity (29)

Route planning for air missions in hostile environments

Abstract: Air mission planning in hostile environments requires that multiple dependent objectives are taken into account. For example, the aircraft must be unharmed in order to perform reconnaissance in an area of interest. Moreover, the risk that the aircraft gets hit depends on the probability that the enemy’s sensors are tracking the aircraft. This paper suggests and analyses an expected cost model for mission routes. It is shown that only a few parameters need to be adjusted for combining different objectives, such as maximizing the survivability, maximizing the probability of performing mission task(s) and minimizing the time in air. The route planning problem is formulated as the optimization problem of finding the route with minimum expected cost. An implemented route planner utilizing particle swarm optimization is used for demonstrating the method with simulations. It is shown that the route planner is able to take dependencies between objectives into account. The conclusion is that the method is useful f...

An Air-to-Ground Combat Survivability Model

Abstract: A survivability model can be a useful component of a tactical support system able to aid fighter pilots to assess the risk of getting hit by enemy fire from ground-based threats. This work identifies three desirable properties of such a model: it should allow for evaluating actions; it should enable domain experts to incorporate their knowledge; and it should represent uncertainties both regarding the locations of the threats as well as their future actions. A survivability model is suggested, which calculates the probability that the aircraft can fly a route unharmed and allows for routes of different lengths to be compared. A domain expert can describe the threats by specifying the risk of getting hit at a position of the route without having to consider the earlier actions of the aircraft and the threats. Three different threat models are suggested and compared. The influence of uncertainties regarding the positions of the threats is studied by calculating the probability density function for the survi...

An environment-driven ontological approach to requirements elicitation for safety-critical systems

Abstract: The environment, where a safety critical system (SCS) operates, is an important source from which safety requirements of the SCS can originate. By treating the system under construction as a black box, the environment is typically documented as a number of assumptions, based on which a set of environmental safety requirements will be elicited. However, it is not a trivial task in practice to capture the environmental assumptions to elicit safety requirements. The lack of certain assumptions or too strict assumptions will either result in incomplete environmental safety requirements or waste many efforts on eliciting incorrect requirements. Moreover, the variety of operating environment for an SCS will further complicate the task, since the captured assumptions are at risk of invalidity, and consequently the elicited requirements need to be revisited to ensure safety has not been compromised by the change. This short paper presents an on-going work aiming to 1) systematically organize the knowledge of system operating environment and, 2) facilitate the elicitation of environmental safety requirements. We propose an ontological approach to achieve the objectives. In particular, we utilize conceptual ontologies to organize the environment knowledge in terms of relevant environment concepts, relations among them and axioms. Environmental assumptions are captured by instantiating the environment ontology. An ontological reasoning mechanism is also provided to support elicitation of safety requirements from the captured assumptions.

Understanding Team Effectiveness in a Tactical Air Unit

Abstract: Effective team work is regarded as a key factor for success in missions performed by fighter aircraft in a Tactical Air Unit TAU. Many factors contribute to how a team will succeed in their mission. From the existing literature on teamwork, Salas, Sims and Burke [1], suggested five main factors and three supporting mechanisms for effective team work. These were proposed as the "Big Five" of teamwork. This article investigates if the model offered by Salas et al. is applicable to a TAU of fighter aircraft. Semi-structured interviews were carried out with six fighter pilots. The results of these interviews imply that the model has relevance for the teamwork in a TAU. Moreover, this paper discusses implications for the design of future decision-support systems that support team effectiveness.

A modular fluid actuator system

Abstract: The present invention regards a modular fluid actuator system provided for generating a relative motion between a first fluid transfer chamber (2, 19') of a first module unit (11, 47) and a piston rod arrangement (5) in an axial direction (X) The modular fluid actuator system (3) comprises a fluid supply(18), a valve device (13, 14) coupled to the fluid supply (18) and to the first fluid transfer chamber (2, 19'), a control unit (15) coupled to the valve device (13, 14) for controlling the relative motion between the first fluid transfer chamber (2, 9') and the piston rod arrangement (5), the first fluid transfer chamber (2, 19')is coupled to a first sleeve portion (29') exhibiting a first expandable hollow space(35)arranged for fluid communication with the valve device (13, 14) via the first fluid transfer chamber (2, 19') The first expandable hollow space (35) is arranged to provide a clamping action of the first sleeve portion (29') to the piston rod arrangement (5) when the first expandable hollow space (35) is pressurised by means of said fluid communication

The effect of variations in temperature cycling profile and mechanical properties of solder on thermo-mechanical reliability of a lead-free BGA package

Abstract: The paper investigates the effect of variations both in temperature cycling profile and in SAC305 solder Young's modulus in the PBGA256 package on the thermo-mechanical reliability. FE simulations quantify the effect of cycle reduction and counting techniques by introducing different temperature profiles having identical dwell- and period time characteristics. A difference of 30% in predicted accumulated creep strain energy density per cycle has been determined for the studied profiles. Under the provided modelling assumptions and simplifications, the maximum variation of the thermal fatigue life of SAC305 solder joints is within 30% as the result of experimentally determined Young's modulus variation in as-delivered packages.

Shock absorbing arrangement configured to withstand impact shock

Abstract: The present disclosure relates to a shock absorbing arrangement suitable e.g. for ship installed structures comprising a rod, a resilient member arranged in connection to the rod, a structure element and a locking member arranged in connection to the structure element. The locking member is arranged to detachably lock the structure element at a resting position at the rod and the locking member, or the structure element, is supported by the resilient member. The resilient member is configured such that a spring force of the resilient member acts to maintain the structure element essentially at the resting position at the rod. The locking member is further configured to release the structure element from the resting position when being exposed to a force exceeding a predetermined holding force, whereupon the resilient member acts to reinstate the locking of the structure element at the resting position at the rod. The present disclosure further relates to a shock absorbing structure comprising such shock absorbing arrangements.

Navigation with SAR and 3D-map aiding

Abstract: This paper presents a method for matching spotlight Synthetic Aperture Radar (SAR) images with a georeferenced 3D-map as means for navigational aid. A hypothesis of the flying platform's absolute position, velocity and direction — which later can be used to correct the inertial navigation system — is attained by image matching and optimization. A projective model with 6 DoF is used to create a simulated SAR image from a 3D map. The parameters of the projective model represents the most important of the platform's navigation state, and these are adjusted by Chamfer matching the captured SAR image to simulated ones. The performance is demonstrated on real spotlight SAR images and 3D-map, and the error is shown to be only a few pixels in average, which in our case is about 3 meters.

Pulsed radar system and method of operating a pulsed radar system

Abstract: The invention relates to a method for operating a pulsed radar system, wherein the pulsed radar system comprises a transmitting antenna, configured to transmit transmission signals, a receiving antenna, configured to receive reflected signals and a signal generating means, configured to generate transmission signals. The method comprises the steps of generating a first transmission signal at a first centre frequency, generating a second transmission signal at a second centre frequency and transmitting the first and the second transmission signals during a predefined transmission time window. The first transmission signal is significantly longer than the second transmission signal. The transmission of the second transmission signal starts during or at the end of the transmission of the first transmission signal and ends essentially at the end of the transmission time window. When the first and/or second transmission signal hits a target a first reflected signal and/or a second reflected signal is generated, wherein the centre frequency of the first reflected signal correlate to the centre frequency of the first transmission signal and the centre frequency of the second reflected signal correlate to the centre frequency of the second transmission signal, and wherein the method further comprises the method step of receiving the first and/or second reflected signal.

On Safety Solutions in an Assembly HMI-Cell

Abstract: The increased diffusion of cooperation between humans and robotics in manufacturing systems is one of the next things to implement within robotics. Since the computer power gets more and more power ...

Shielding effectiveness study of two fabrics with microwave properties before and after high power irradiation

Abstract: Over the past decade several applications for fabrics with electromagnetic properties have emerged, most of them relating to garments, including jackets with built-in antennas and workwear with increased radar visibility. Beside these have surfaced two protective applications, namely to protect transports of confidential equipment from discovery and identification; and to protect sensitive apparatus from damage by high power electromagnetic irradiation e.g. in field operations. In this paper results are presented from measurement of shielding effectiveness before and after high power radiation for two types of fabrics under consideration for the latter applications. Shielding effectiveness measurements have been conducted between 1 and 18 GHz while the high power irradiation was given with 28 kV/m at 1300 MHz.

Secure data transfer

Abstract: The disclosure relates to a system, devices and methods for distributing and using a communication scheme for way to enable secure communication between communication nodes in a network A method comprises determining (S1), in the network node, a set of available IP addresses and a set of ports, dividing (S2), in the network node, a time frame in time slots, associating (S3), in the network node, each time slot with an IP address, with a port associated with the IP address and with a unique cryptographic key, distributing (S4), from the network node, the communication scheme to the communication node, receiving (S100), in the communication node, the communication scheme and communicating (S300), in the communication node, with another communication node in possession of a corresponding communication scheme by hopping between the IP addresses and ports according to the communication scheme and encrypting the communication using the unique cryptographic key

Comparing Multi-Objective Approaches for Air Route Planning in Hostile Environments

Abstract: Route planning for aircraft that should fly in hostile environmentscan be regarded as a multi-objective optimization problem, where the route should enable the aircraft to accomplish its mission tasks with a minimum risk exposure and minimum fuel consumption. This work compares different approaches for multi-objective route planning that have been suggested in the literature regarding their formulation of objectives as well as how they handle the decision maker’s preferences. It is concluded that most route planners minimize threat exposure and route length, but can also include altitude and flight dynamics constraints. Preferences regarding the objectives can be included in the route planning algorithms with weights or priorities. An alternative approach is that the route planner suggests a number of routes and thereafter lets the decision maker select the best one.