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Stroop color-word test (STW) is a reliable method that has been used in laboratory to induce stress to the subject. This paper describes the development of Stroop color-word Test which was implemented based on five sections of test condition: i. Introductory Section (IS), ii. Resting Section (RS), iii. Congruent Section (CS), iv. Incongruent Section 1 (ICS-1), and v. Incongruent Section 2 (ICS-2). This test condition was identified from normal state until the highest stress state. Psychology experiment and MATLAB software were used in implementing the stress test. Electroencephalogram (EEG) signal of six healthy subjects was recorded while conducting this test. Power Spectral Density (PSD) was computed and analyzed. Results found that PSD can differentiate the level of stress from normal until the highest stress state. As such, it can be used as computer-assisted tool for stress detection.

This study aims to evaluate the effect of workstation type on the neural and vascular networks of the prefrontal cortex (PFC) underlying the cognitive activity involved during mental stress. Workstation design has been reported to affect the physical and mental health of employees. However, while the functional effects of ergonomic workstations have been documented, there is little research on the influence of workstation design on the executive function of the brain. In this study, 23 healthy volunteers in ergonomic and non-ergonomic workstations completed the Montreal imaging stress task, while their brain activity was recorded using the synchronized measurement of electroencephalography and functional near-infrared spectroscopy. The results revealed desynchronization in alpha rhythms and oxygenated hemoglobin, as well as decreased functional connectivity in the PFC networks at the non-ergonomic workstations. Additionally, a significant increase in salivary alpha-amylase activity was observed in all participants at the non-ergonomic workstations, confirming the presence of induced stress. These findings suggest that workstation design can significantly impact cognitive functioning and human capabilities at work. Therefore, the use of functional neuroimaging in workplace design can provide critical information on the causes of workplace-related stress.

Blind techniques and algorithms for Multiple-Input Multiple-Output (MIMO) signals interception have recently attracted a great deal of research efforts. This is due to their important applications in the military and civil telecommunications domains. One essential step in the signal interception process is to blindly recognize the modulation scheme of the MIMO signals. This process is formally called Modulation Classification (MC). This paper discusses the modulation classification for MIMO systems and presents a comprehensive and critical literature review of the existing MC algorithms for MIMO systems; where possible, gaps in the knowledge base are identified and future directions for the research work are suggested.

A number of Claimer-Reporter-Witness based schemes (also called witness node based schemes) have been proposed to solve the problem of clone node attack or node replication attack which brings severe threats to WSNs. Node replication attack is an application independent attack in which an adversary first physically captures and then compromises a sensor node in the network and after creating clones or replicas of the compromised nodes; he/she surreptitiously deploys them at strategic positions of the network. The approaches used by the existing Claimer Reporter Witness-based detection schemes tradeoff between the higher detection probability for detecting clones and various overheads. The communication costs along with the memory and processing costs need to be measured to find out the gain from tradeoff. This is the first such work in which we have developed analytical framework to measure various costs for our proposed distributed clone detection protocol RAND and the other existing distributed schemes for clone detection. Moreover, we have also presented numerical results to demonstrate the impact of network size and the number of selected witnesses on these costs. Our results show that a significant amount of resources are required by the chosen CRW based schemes for detecting clones. Our comprehensive cost model can be used as a framework for estimating the costs of different CRW based protocols and can aid the researchers to choose the most efficient protocol for detecting clones in the network as well as estimate the resource requirements of the network to develop effective schemes in future.

In this paper we propose a simple divided spectrum balanced detection (DSBD) for spectral amplitude coding (SAC) optical code division multiple access (OCDMA) systems. SAC OCDMA systems are limited by phase induced intensity noise (PIIN), which is a signal dependent source of noise. Our proposed technique reduces the PIIN by dividing the spectrum of the signal into two or more, and detecting each spectrum by a different photodiode. The DSBD scheme reduces the detected optical power at photodetection, thus resulting in a higher mitigation of the PIIN. Theoretical results show that DSBD demonstrate noticeable improvement over traditional balanced detection technique, for example an up to 33% increase in the number of active users can be achieved, and at least 1 × 10 −3 b/s Hz increase in the spectral efficiency is obtained. However, the SDBD is more complex and append more constrains on system components.

In this paper, we investigate the effect of multiple input multiple output (MIMO) systems on the performance of the multicarrier direct sequence code division multiple access (MC DS-CDMA) system operating over independent identically distributed (i.i.d) η – μ flat fading environment in terms of average error probability and average channel capacity. We derive the instantaneous signal to interference noise ratio (SINR) at the output of the receiver. Hence, based on moment generating function (MGF) approach, we obtain the probability density function (PDF) of the instantaneous SINR. Closed form expressions of average error probabilities for the system are developed and expressed in Appell's and Lauriccella's hypergeometric functions. Furthermore, we achieve exact expression of average channel capacity for the system. Finally, we validate our results using Monte Carlo simulation technique and also compare with those already available in the literature.

In this paper, we show details of zero cross correlation (ZCC) code development and investigate performance by measuring bit-error-rates compared to other optical code division multiple access (OCDMA) codes using Avalanche photodiode (APD) and PIN photodetector. We present a configuration to determine how optical OCDMA systems can be applied with PIN and APD photodetector. Analysis of Avalanche photodiode gain optimization is discussed in ZCC code system. We also present analytical and numerical theoretical results for data transmission of spectrally encoded incoherent OCDMA signal and how signal-noise is being affected by using these two photodetectors.

This paper investigates the performance of vector combinatorial (VC) code for spectral amplitude coding optical code-division multiple-access (SAC-OCDMA) system using a newly proposed subtract exclusive OR detection (SED) technique. VC code is constructed using Euclidean vector and algebraic ways. One of the important properties of this code is that the maximum cross correlation is one, which means that multi-user interference (MUI) and phase induced intensity noise (PIIN) are reduced. The weight for the VC code can be any positive integer number. The system performance was evaluated by comparing the theoretical studies using related equations and simulation results taken from the commercial optical systems, “VPI™ TransmissionMaker 7.1”. Significant improvement in system performances has been observed when the proposed SED technique employing VC code was applied compared to other codes that utilize conventional balance detection techniques for spectral amplitude coding.

We have proposed a new Multi-Diagonal (MD) code for Spectral Amplitude – Coding Optical Code Division Multiple Access (SAC-OCDMA). Although this new MD code has many properties, one of the important properties of this code is that the cross correlation is always zero. Simplicity in code construction and flexibility in cross correlation control has made this code a compelling candidate for future OCDMA applications. The Multiple access interference (MAI) effects have been successfully and completely eliminated. Based on the theoretical analysis MD code is shown here to provide a much better performance compared to Modified Quadratic Congruence (MQC) code and Random Diagonal (RD) code. Proof-of-principle simulations of encoding with 5 and 10 users with 622 Mb/s data transmission at a BER of 10 −12 have been successfully demonstrated together with the DIRECT detection scheme.

A zero cross-correlation (ZCC) code is proposed to reduce the impact of system impairment and multiple access interference (MAI) in spectral amplitude coding optical code division multiple access (SAC–OCDMA) system. Bit-error-rate (BER) performance is derived taking into account the effect of some noises. The key to an effective OCDMA system is the choice of efficient address codes with good or almost zero correlation properties for encoding the source. The use of ZCC code can eradicate phase induced intensity noise (PIIN) which will contribute to better BER. Thus, we demonstrate, theoretically, the performance of optical ZCC code. It is shown that optical ZCC code can accommodate more users simultaneously for the typical error rate of optical communication system of 10 −9 . The result indicates that the established system not only preserves the capability of suppressing MAI, but also improves bit-error-rate performance as compared to the conventional coders.