An autonomous GNSS anti-spoofing technique

open3siIn recent years, the problem of Position, Navigation and Timing (PNT) resiliency has received significant attention due to an increasing awareness on threats and the vulnerability of the current GNSS signals. Several proposed solutions make uses of cryptography to protect against spoofing. A limitation of cryptographic techniques is that they introduce a communication and processing computation overhead and may impact the performance in terms of availability and continuity for GNSS users. This paper introduces autonomous non cryptographic antispoofing mechanisms, that exploit semi-codeless receiver techniques to detect spoofing for signals with a component making use of spreading code encryption.openCaparra, Gianluca; Wullems, Christian; Ioannides, Rigas T.Caparra, Gianluca; Wullems, Christian; Ioannides, Rigas T

Low-optical-loss, low-resistance Ag/Ge based ohmic contacts to n-type InP for membrane based waveguide devices

We present the development of Ag/Ge based ohmic contacts to n-type InP with both low contact resistances and relatively low optical losses. A specific contact resistance as low as 1.5×10-6 O cm2 is achieved by optimizing the Ge layer thickness and annealing conditions. The use of Ge instead of metal as the first deposited layer results in a low optical absorption loss in the telecommunication wavelength range. Compared to Au based contacts, the Ag based metallization also shows considerably reduced spiking effects after annealing. Contacts with different lengths are deposited on top of InP membrane waveguides to characterize the optical loss before and after annealing. A factor of 5 reduction of the propagation loss compared to the conventional Au/Ge/Ni contact is demonstrated. This allows for much more optimized designs for membrane photonic devices

What do older people do when sitting and why? Implications for decreasing sedentary behaviour

Background and Objectives: Sitting less can reduce older adults’ risk of ill health and disability. Effective sedentary behavior interventions require greater understanding of what older adults do when sitting (and not sitting), and why. This study compares the types, context, and role of sitting activities in the daily lives of older men and women who sit more or less than average. Research Design and Methods: Semistructured interviews with 44 older men and women of different ages, socioeconomic status, and objectively measured sedentary behavior were analyzed using social practice theory to explore the multifactorial, inter-relational influences on their sedentary behavior. Thematic frameworks facilitated between-group comparisons. Results: Older adults described many different leisure time, household, transport, and occupational sitting and non-sitting activities. Leisure-time sitting in the home (e.g., watching TV) was most common, but many non-sitting activities, including “pottering” doing household chores, also took place at home. Other people and access to leisure facilities were associated with lower sedentary behavior. The distinction between being busy/not busy was more important to most participants than sitting/not sitting, and informed their judgments about high-value “purposeful” (social, cognitively active, restorative) sitting and low-value “passive” sitting. Declining physical function contributed to temporal sitting patterns that did not vary much from day-to-day. Discussion and Implications: Sitting is associated with cognitive, social, and/or restorative benefits, embedded within older adults’ daily routines, and therefore difficult to change. Useful strategies include supporting older adults to engage with other people and local facilities outside the home, and break up periods of passive sitting at home

Transfer of genetic information via isolated mammalian chromosomes

Recombination of genetic information from different origin has provided insight in many aspects of the genetic mechanisms of the living cell. These aspects concern the location of genes on chromosomes, the regulation of gene expression and the interaction of different genes in the determination of a particular phenotype. The classic process to produce such new genetic combinations is the conjugation of a male and female gamete, resulting in the formation of a zygote. Genetic studies at the molecular level with micro organisms, have lead to the discovery of other processes for the formation of new genetic combinations. One of these processes is genetic transformation, defined as the integration and expression of a small piece of deoxyribonucleic acid (DNA), extracted from donor cells and introduced into the genome of the recipient cells. A second process is transduction, which is defined as the bacteriophage mediated transfer of genetic information from one bacterium (donor) to another (recipient). The bacteriophage involved, multiplies in the donor bacterium and, after lysis, it is able to transfer genetic information of the donor to recipient bacteria upon infection

Performance measurement and lumped parameter modelling of single server flowlines subject to blocking : an effective process time approach

The present paper extends the so-called Effective Process Time (EPT) approach to single server flowlines with finite buffers and blocking. The power of the EPT approach is that it quantifies variability in workstation process times without the need to identify each of the contributing disturbances, and that it directly provides an algorithm for the actual computation of EPTs. It is shown that EPT realizations can be simply obtained from arrival and departure times of lots, by using sample path equations. The measured EPTs can be used for bottleneck analysis and for lumped parameter modeling. Simulation experiments show that for lumped parameter modeling of flowlines with finite buffers, in addition to the mean and variance, offset is also a relevant parameter of the process time distribution. A case from the automotive industry illustrates the approach

'It's pathological': Exploring gaps in the whole-systems approach for managing operations and safety risk at a fully automatic rail level crossing

There are 23,500 level crossings in Australia. In these risky environments, it is important to understand what human factor issues are present and how road users and pedestrians engage with crossings. On-site observations were performed over a 2-day period at a 3-track active crossing. This was followed by 52 interviews with level crossing users. Over 700 separate violations were recorded, with representations in multiple categories (e.g. going through flashing lights >2s after starting flashing; stopping on crossing). Time stamping revealed that the crossing was active for 59% of the time in some morning periods and trains could take up to 4-min to arrive following first activation. Users experienced frustration due to delays caused by the frequency of trains, which increased likelihood of risk-taking. Analysis of interview data identified themes associated with congestion, safety, and violations. This work offers insight into context specific issues associated with active level crossing protection