Load shedding and the energy security of Republic of South Africa

Studies on energy security can be found in many academic publications and in government and think-tank reports. Main goal of this article is to present the energy system in the Republic of South Africa, to discuss the phenomenon of load shedding and it indication of proposed changes required to existing solutions. Authors based their research on available literature newspapers articles, direct observation and the interviews with the residents of Johannesburg. South African’s economy is the second largest in Africa, just behind Nigeria. It accounts for 24% of continent’s GDP. It is ranked as an upper-middle income economy by the World Bank. The major producer and distributor of electricity in RSA is Eskom, which provides over 95% of the country’s energy usage. Load-shedding, also referred to as rolling blackout, is an intentionally electrical power shutdown. In South Africa it affect entire country

The Analysis of Offenses in Inland Navigation in Poland 2013-2017

The article presents an analysis of offenses in inland navigation in 2013-2017, based on the number and reasons for issuing fines by Offices of Inland Navigation in Poland. In the investigated period, in Poland, over 1,300 fines were issued on the basis of five articles of the Act of 21st of December 2000 on Inland Navigation. Based on the collected data, the most common reasons for punishing crews of inland vessels were determined and the impact of these offenses on the safety of inland navigation in Poland was identified. In addition, recommendations for changes in the classification of offenses were presented due to the too wide spectrum of individual articles, which adversely affects the ability to interpret the most common offenses and makes it difficult to assess the causes and effects of their occurrence

Conception of decision support system for resilience management of seaport supply chains

The target of this paper is to present the preliminary concept of decision support system for seaports supply chain risk management in the aspect of vulnerability and resilience engineering. As a result, there is discussed a literature review connected with resilience engineering of seaport infrastructure systems and their supply chains. Later, the decision support system conception is investigated. The developed solution is to be based on the What if? approach and Bow-Tie method. The work ends up with summary and directions for further research

Life Cycle Costs of passenger transportation system : Case study of Wroclaw city agglomeration

In the article authors are interested in the issues of LCC analysis implementation in the area of passenger transportation systems performance. In the first step of research analysis, there is provided a briefly literature overview of the analysed research area. Thus, the applicability of LCC analysis is investigated on the existing passenger transportation system located in Lower Silesia, Poland

Wiener kernel analysis of inner ear function in the American bullfrog

The response of 17 primary auditory nerve fibers in the American bullfrog (Rana catesbeiana) to acoustic noise stimulation of the tympanic membrane was recorded. For each fiber, the first- and second-order Wiener kernels, k(1)(tau(1)) and k(2)(tau(1),tau(2)), were computed by cross correlation of the stimulus and the response. The kernels revealed amplitude and phase characteristics of auditory filters of both phase-locking and non-phase-locking fibers. Wiener kernels of high- and midfrequency fibers (best frequency, BF>500 Hz), implied a simple sandwich model, consisting of a cascade of a linear bandpass filter, a static nonlinearity, a linear low-pass filter, and a spike generator. The bandpass filter was at least of order 7, and had a linear phase response, for both the high- and the midfrequency fibers. Averaged across fibers, filter order 2, and cutoff frequency 451 Hz for the second filter in the model was observed. The responses of low-frequency fibers (BF<500 Hz) could not be fit with the sandwich model, because the Fourier transform K-2(f(1),f(2)) of the second-order Wiener kernel showed significant components at off-diagonal frequencies f(1) not equal+/-f(2). The presence of these off-diagonal components shows that, in addition to the phase and gain characteristics of auditory filters, the Wiener kernel analysis reveals nonlinear two-tone interactions