Extra-wide-angle parabolic equations in motionless and moving media

Wide-angle parabolic equations (WAPEs) play an important role in physics. They are derived by an expansion of a square-root pseudo-differential operator in one-way wave equations, and then solved by finite-difference techniques. In the present paper, a different approach is suggested. The starting point is an extra-wide-angle parabolic equation (EWAPE) valid for small variations of the refractive index of a medium. This equation is written in an integral form, solved by a perturbation technique, and transformed to the spectral domain. The resulting split-step spectral algorithm for the EWAPE accounts for the propagation angles up to 90° with respect to the nominal direction. This EWAPE is also generalized to large variations in the refractive index. It is shown that WAPEs known in the literature are particular cases of the two EWAPEs. This provides an alternative derivation of the WAPEs, enables a better understanding of the underlying physics and ranges of their applicability, and opens an opportunity for innovative algorithms. Sound propagation in both motionless and moving media is considered. The split-step spectral algorithm is particularly useful in the latter case since complicated partial derivatives of the sound pressure and medium velocity reduce to wave vectors (essentially, propagation angles) in the spectral domain.

Electromagnetic Wave Scattering from a Moving Medium with Stationary Interface across the Interluminal Regime

This paper extends current knowledge on electromagnetic wave scattering from bounded moving media in several regards. First, it complements the usual dispersion relation of moving media, ω(θk) (θk: phase velocity direction, associated with the wave vector, k), with the equally important impedance relation, η(θS) (θS: group velocity direction, associated with the Poynting vector, S). Second, it explains the interluminal-regime phenomenon of double-downstream wave transmission across a stationary interface between a regular medium and the moving medium, assuming motion perpendicular to the interface, and shows that the related waves are symmetric in terms of the energy refraction angle, while being asymmetric in terms of the phase refraction angle, with one of the waves subject to negative refraction, and shows that the wave impedances of the two transmitted waves are equal. Third, it generalizes the problem to the case where the medium moves obliquely with respect to the interface. Finally, it highlights the connection between this problem and a spacetime modulated medium.

Funny and meaningful: media messages that are humorous and moving provide optimal consolation in corona times

During the first months of the corona crisis, people worldwide produced and shared thousands of uplifting (e.g., humorous, moving) media messages. The six studies reported here empirically tested the consolatory effects of viewing such positive media messages in the US, The Netherlands, and the UK. I compared the impact of humorous and moving (i.e., touching, heartwarming) messages, as they provide different kinds of well-being: hedonic versus eudaimonic. Studies 1–3 had correlational designs. Largely in line with the hedonic versus eudaimonic well-being framework, the results suggested that humorous messages lift people’s spirits by providing pleasure, while moving messages lift people’s spirits by providing realism, optimism, and by illustrating core human values. Studies 4–6 used a pre- and post-measure of negative and positive emotions. The results showed that viewing non-moving humorous messages significantly reduced negative emotions but did not increase positive emotions. Viewing non-humorous moving messages reduced negative emotions and increased positive emotions in the US and UK, but not in The Netherlands. Finally, viewing messages that are both humorous and moving reduced negative emotions and increased positive emotions in all samples, implying they are particularly valuable as mood-enhancers during crises. The practical and theoretical implications of these findings are discussed.

PENGOLAHAN LINDI (LEACHEATE) DENGAN METODE MOVING BED BIOFILM REACTOR (MBBR) DENGAN PROSES AEROBIK-ANOKSIK UNTUK MENURUNKAN KONSENTRASI COD, TSS, DAN AMONIA.

ABSTRACT Leachate contains high levels of organic matter, TSS and ammonia. Moving Bed Biofilm Reactor (MBBR) is a biological treatment that can reduce the concentration contained in leachate. The purpose of this study was to determine the ability of MBBR to reduce the content of organic matter, TSS, and ammonia, by using variations in the detention time of aerobic-anoxic processes and sticky media. This research is a laboratory scale research. Leachate samples came from the Kotawaringin Timur TPA Inlet. The reactor is operated in batches. During the aerobic process the moving media is assisted by an aerator pump and submersible pump, while in the anoxic process it is only from a submersible pump. The MBBR processing used has a capacity of 5L with a media capacity of 2L. The variations of the media used were K1 and K3 caldness, while the aerobic detention time was 14.5 hours - anoxic 10 hours and aerobic 10 hours anoxic 7 hours. The results obtained show that MBBR can be used to treat leachate. The best decrease in COD, TSS, and ammonia concentrations occurred in K1 media with 14.5-anoxic 10-hour aerobic detention time with a reduction of 74.8%, 93.14%, and 83.72%.

High-Frequency Electrodynamics of Slow Moving Media Taking into Account the Specular Reflection

The paper presents the results of constructing the physical and mathematical model of high-frequency electromagnetic waves propagation in slowly moving media of finite dimensions, which takes into account the phenomena of specular reflection of these waves. The constructed model is based on formulas designed to determine the speed of electromagnetic waves propagation in slowly moving media of finite dimensions, as well as on equations designed to describe these waves. The advantageous feature of these equations is that they take into account the Fresnel drag coefficient for electromagnetic waves propagation speed. The approach to solving of these equations, as well as the approach to modeling of the process of electromagnetic waves propagation in slowly moving media of finite dimensions, based on the use of a difference scheme, in which the motion of these media is taken into account, is proposed. It has been determined that the proposed model and approaches can be used in solving problems related to the construction of receiving-transmitting paths, as well as in solving problems of aeroacoustics.

Real Wastewater Treatment Using a Moving Bed and Wastewater-Borne Algal–Bacterial Consortia with a Short Hydraulic Retention Time

Algal–bacterial consortium is a promising technology, combined with wastewater treatment plants, because algae produce molecular oxygen for nitrification and organic removal and reduce carbon dioxide emissions. However, algal–bacterial consortia based on suspended growth require a relatively long hydraulic retention time (HRT) of 4 d to 6 d for removal of organic matter and nutrients. For the algal–bacterial consortia in a photobioreactor (PBR) containing a moving bed, the organic matter and nutrient removal and the community structure of algal–bacterial consortia were investigated to determine the performance under a relatively short HRT of 2.5 d. Moving media containing algal–bacterial consortia enhanced the photosynthetic oxygen concentration (0.2 mg dissolved oxygen (DO)·L−1 to 5.9 mg DO·L−1), biochemical oxygen demand removal (88.0% to 97.2%), ammoniacal nitrogen removal (33.8% to 95.3%), total nitrogen removal (61.6% to 87.7%), total phosphate removal (66.4% to 88.7%), algal growth (149.3 mg algae·L−1 to 285.4 mg algae·L−1), and settleability (algae removal efficiency of 20.6% to 71.2%) compared with those of a PBR without moving media (SPBR). Although biomass uptake was the main mechanism for nutrient removal in the SPBR, both biomass uptake and denitrification were the main mechanisms in the PBR with moving media (MBPBR). The bacterial community also changed under the moving media condition. This study shows that moving media might be an essential parameter for PBRs with a short HRT to enhance nutrient removal and settleability.

Platformization, panentertainment and piracy: What the fast-changing Chinese mediasphere tells us about technology, policy and the state

The recent rise of media platforms in China is in line with China’s ‘going out’ policy of the past two decades, as well as with the Internet Plus and other state sponsored national information technology-related initiatives. The intellectual property-centred pan entertainment strategy further signals a change in the platforms’ content production, distribution and reception. The spin-off driven, derivative platform culture means content, and intellectual property, have become the front and centre of this new digital economy. This article examines the fast-moving media and cultural ecosystem in China in relation to the state, globalization, technology and piracy. More specifically, it looks at platform/distribution in the context of convergence while investigates questions of online piracy and copyright enforcements. This article concludes that China’s global ambition, coupled with its copyright-centred platform economy, marks a historical moment in which China transitions from being a copyright violator to a copyright enforcer.