Synthetic Profiles Research Articles

Modelling charge profiles of electric vehicles based on charges data.

Background: The correct design of electric vehicle (EV) charging infrastructures is of fundamental importance to maximize the benefits for users and infrastructure managers. In addition, the analysis and management of recharges can help evaluate integration with auxiliary systems, such as renewable energy resources and storage systems. EV charging data analysis can highlight informative behaviours and patterns for charging infrastructure planning and management. Methods: We present the analysis of two datasets about the recorded energy and duration required to charge EVs in the cities of Barcelona (Spain) and Turku (Finland). In particular, we investigated hourly, daily and seasonal patterns in charge duration and energy delivered. Simulated scenarios for the power request at charging stations (CSs) were obtained using statistical parameters of the Barcelona dataset and non-parametric distributions of the arrivals. Monte Carlo simulations were used to test different scenarios of users' influx at the CSs, and determine the optimal size of an integrated renewable energy system (RES). Results: This study highlighted the difference between fast and slow charging users' habits by analysing the occupancy at the charging stations. Aside from the charge duration, which was shorter for fast charges, distinct features emerged in the hourly distribution of the requests depending on whether slow or fast charges are considered. The distributions were different in the two analysed datasets. The investigation of CS power fluxes showed that results for the investment on a RES could substantially vary when considering synthetic input load profiles obtained with different approaches. The influence of incentives on the initial RES cost were investigated. Conclusions: The novelty of this work lies in testing the impact of different approach to design synthetic profiles in the determination of the optimal size of a photovoltaic (PV) system installed at a charging infrastructure, using the economic criterion of the net present value (NPV).

Elastic Impedance Simultaneous Inversion for Multiple Partial Angle Stack Seismic Data with Joint Sparse Constraint

Elastic impedance (EI) inversion for partial angle stack seismic data is a key technology in seismic reservoir prediction within the oil and gas industry. EI inversion provides a consistent framework to invert partial angle stack seismic data, just as the AI inversion does for post-stack data. The commonly used EI inversion process is angle by angle. Hence, the inverted EI for different angles may be nonconforming, especially for the seismic data with a low signal-to-noise ratio. This paper proposes to simultaneously invert multiple partial angle stack seismic data to obtain EI for different angles at once. To obtain conformable EI, we used the joint sparse constraint on the reflection coefficients for different angles. Then, the objective function for simultaneous EI inversion was constructed. Next, synthetic seismic data profiles with three different angles were used to show the superiority of the proposed EI inversion method compared to the conventional method. At last, a real seismic data line was used to test the feasibility of the proposed method in practice. The inversion results of synthetic data and real data showed that it provides an effective new alternative method to estimate EI from partial stack seismic data.

Hydrogen emission from accretion and outflow in T Tauri stars

ABSTRACT Radiative transfer modelling offers a powerful tool for understanding the enigmatic hydrogen emission lines from T Tauri stars. This work compares optical and near-IR spectroscopy of 29 T Tauri stars with our grid of synthetic line profiles. The archival spectra, obtained with VLT/X-Shooter, provide simultaneous coverage of many optical and infrared hydrogen lines. The observations exhibit similar morphologies of line profiles seen in other studies. We used the radiative transfer code torus to create synthetic H α, Pa β, Pa γ, and Br γ emission lines for a fiducial T Tauri model that included axisymmetric magnetospheric accretion and a polar stellar wind. The distribution of Reipurth types and line widths for the synthetic H α lines is similar to the observed results. However, the modelled infrared lines are narrower than the observations by ${\approx}80\,{~\rm km\,s}^{-1}$, and our models predict a significantly higher proportion (≈90 per cent) of inverse P-Cygni profiles. Furthermore, our radiative transfer models suggest that the frequency of P-Cygni profiles depends on the ratio of the mass-loss to mass accretion rates and blue-shifted sub-continuum absorption was predicted for mass-loss rates as low as 10−12 M⊙ yr−1. We explore the effect of rotation, turbulence, and the contributions from red-shifted absorption in an attempt to explain the discrepancy in widths. Our findings show that, singularly, none of these effects is sufficient to explain the observed disparity. However, a combination of rotation, turbulence, and non-axisymmetric accretion may improve the fit of the models to the observed data.

Methodology for Generating Synthetic Load Profiles for Different Industry Types

To achieve its climate goals, the German industry has to undergo a transformation toward renewable energies. To analyze this transformation in energy system models, the industry’s electricity demands have to be provided in a high temporal and sectoral resolution, which, to date, is not the case due to a lack of open-source data. In this paper, a methodology for the generation of synthetic electricity load profiles is described; it was applied to 11 industry types. The modeling was based on the normalized daily load profiles for eight electrical end-use applications. The profiles were then further refined by using the mechanical processes of different branches. Finally, a fluctuation was applied to the profiles as a stochastic attribute. A quantitative RMSE comparison between real and synthetic load profiles showed that the developed method is especially accurate for the representation of loads from three-shift industrial plants. A procedure of how to apply the synthetic load profiles to a regional distribution of the industry sector completes the methodology.

Improved techniques to resolve the water column sound speed structure for multibeam ray-tracing

Multibeam bathymetry surveys conducted in highly stratified environments are routinely affected by sound speed errors. The approach proposed here aims to combine measured with synthetic sound speed profiles in order to minimize sound speed errors. The adequacy of synthetic profiles derived from a regional hydrodynamic model and spatiotemporal interpolation is therefore investigated. Ray-tracing comparisons at the 65° launch angle between measured and synthetic profiles demonstrates that the expected depth bias for modeled profiles will be in excess of 1% of water depth. Spatiotemporally interpolating hourly sampled profiles decreases the depth bias up to a factor of three for higher beam angles. Residual sounding depth biases are observed and ascribed to a residual surface sound speed error.

Intra-pulse variability induced by plasmoid formation in pulsar magnetospheres

Context. Pulsars show irregularities in their pulsed radio emission that originate from propagation effects and the intrinsic activity of the source. Aims. In this work, we investigate the role played by magnetic reconnection and the formation of plasmoids in the pulsar wind current sheet as a possible source of intrinsic pulse-to-pulse variability in the incoherent, high-energy emission pattern. Methods. We used a two-dimensional particle-in-cell simulation of an orthogonal pulsar magnetosphere restricted to the plane perpendicular to the star spin axis. We evolved the solution for several tens of pulsar periods to gather a statistically significant sample of synthetic pulse profiles. Results. The formation of plasmoids leads to strong pulse-to-pulse variability in the form of multiple short, bright subpulses, which appear only on the leading edge of each main pulse. These secondary peaks of emission are dominated by the dozen plasmoids that can grow up to macroscopic scales. They emerge from the high end of the hierarchical merging process occurring along the wind current layer. The flux of the subpulses is correlated with their width in phase. Although the full-scale separation is not realistic, we argue that the simulation correctly captures the demographics and the properties of the largest plasmoids, and therefore of the brightest subpulses. Conclusions. The prediction of subpulses at specific pulse phases provides a new observational test of the magnetic reconnection scenario as the origin of the pulsed incoherent emission. High-time-resolution observations of the Crab pulsar in the optical range may be the most promising source to target for this purpose.

Lower uncertainty bounds of diffraction-based nanoparticle sizes.

A self-consistent analysis is reported of traditional diffraction-based particle size determination techniques applied to synthetic diffraction profiles generated with the Patterson approach. The results show that dimensions obtained from traditional techniques utilizing peak fitting or Fourier analysis for single-crystal nanoparticles have best-case error bounds of around 5%. For arbitrarily shaped particles, lower error magnitudes are possible only if the zeroes of the thickness fringes are used. The errors for sizes obtained by integral-breadth- and Fourier-decomposition-based techniques depend on the shape of the diffracting domains. In the case of integral-breadth analysis, crystal shapes which scatter more intensity into the central peak of the rocking curve have lower size errors. For Fourier-decomposition analysis, crystals which have non-uniform distributions of chord lengths exhibit nonlinearities in the initial ranges of the normalized Fourier cosine coefficient versus column length (|A L | versus L) plots, even when the entire rocking curve is used in the decomposition. It is recommended that, in routine analysis, all domain size determination techniques should be applied to all reflections in a diffraction pattern. If there is significant divergence among these results, the 'average particle size(s)' obtained might not be reliable.

A Method For Generating Plane Wave And Zero-Offet Vsp Synthetic Seismograms

Synthetic Vertical Seismic Profiles (VSP) seianograms are a useful aid to the interpretation of VSP re- conds, Plane wave VSP syntherics multiples and mode conversions can be computed rapldly n the frequency domain using a new recursive formulation. The method urilises the concept of "renultanz" phase related reflection and tranamission coefficients for a layer atack. High frequerncy signals can be handled with relative euse. The ability to control the order of the multiple avolds wraparound problems with the discrete Fourier transform. Several examples are used to lhustrate the method with relewance to seismic exploration.

A New Type Of Digital Band - Pass Filter

Digital filtering is mathematical process which provides a means of filtering data numerically. The filtering process can be carried out in the frequency domain to discriminate signal and noise based on the frequency differencesThe digital band-pass frequency filtering has been effectively accomplished using a new type of digital filter. This filter is the result of compolving a boxcar spectral window with a frequency shifted Gaussian function which produces a very smooth transition between the pass-band and the stop-band region. The slope of the filter is controlled by the exponential coefficient of the Gaussian function. For a very narrow pass-band the exponential coefficient also controls the resolution of the filter.Experiments have been done with the Synthetic Vertical Seismic Profiles data to prove the performance of the filter and shows a good results.

Using topic modeling to detect cellular crosstalk in scRNA-seq.

Cell-cell interactions are vital for numerous biological processes including development, differentiation, and response to inflammation. Currently, most methods for studying interactions on scRNA-seq level are based on curated databases of ligands and receptors. While those methods are useful, they are limited to our current biological knowledge. Recent advances in single cell protocols have allowed for physically interacting cells to be captured, and as such we have the potential to study interactions in a complemantary way without relying on prior knowledge. We introduce a new method based on Latent Dirichlet Allocation (LDA) for detecting genes that change as a result of interaction. We apply our method to synthetic datasets to demonstrate its ability to detect genes that change in an interacting population compared to a reference population. Next, we apply our approach to two datasets of physically interacting cells to identify the genes that change as a result of interaction, examples include adhesion and co-stimulatory molecules which confirm physical interaction between cells. For each dataset we produce a ranking of genes that are changing in subpopulations of the interacting cells. In addition to the genes discussed in the original publications, we highlight further candidates for interaction in the top 100 and 300 ranked genes. Lastly, we apply our method to a dataset generated by a standard droplet-based protocol not designed to capture interacting cells, and discuss its suitability for analysing interactions. We present a method that streamlines detection of interactions and does not require prior clustering and generation of synthetic reference profiles to detect changes in expression.

Dynamic wake analysis of a wind turbine providing frequency support services

The participation of wind farms in providing ancillary services is an asset for the power system and one way to maintain a strong grid with the increasing penetration of renewable energy sources. Research has shown this to be feasible for wind farms by using efficient prediction and sophisticated control systems. In some parts of the world, strict grid codes are already being implemented that require wind farms to provide ancillary services. Moreover, the primary reserve market in Europe is moving towards shorter procurement periods, providing wind farms an opportunity to more efficiently optimise their resources based on short term forecasts. It can however be challenging for the wind farms to efficiently participate in grid frequency support services, especially for primary reserve services. The reason behind this is the requirement of quick activation and deactivation of power reserve margin for services such as Frequency Containment Reserve (FCR) and Fast Frequency Response (FFR). A full activation of the contracted reserve is required within seconds of a grid frequency dip. A sudden change in wind turbine dynamics is expected to have an impact on the wake behind the wind turbine. The wake effect within a wind farm is taken into thorough consideration in its design process. The effect on the wake due to the wind turbines participating in fast response ancillary services however, remains unexplored. This is a matter of greater concern for wind farms with a high capacity density. To this end, the main contribution of this article is to observe the effect of ancillary service based control system on the wake effect of a wind turbine. Additionally, the capability of developed wind turbines controllers to follow primary reserve services are also tested. FFR and FCR services are tested for a range of frequency designs, these include both synthetic and actual grid frequencies. The synthetic frequency profiles are designed to replicate both fast and slow frequency variations in order to analyse the impact on wake behaviour. The simulations are performed for low and high wind speed including constant as well as turbulent winds.

Binary-object spectral-synthesis in 3D (BOSS-3D)

Context. To quantitatively decode the information stored within an observed spectrum, detailed modelling of the physical state and accurate radiative transfer solution schemes are required. The accuracy of the model is then typically evaluated by comparing the calculated and observed spectra. In the analysis of stellar spectra, the numerical model often needs to account for binary companions and 3D structures in the stellar envelopes. The enigmatic binary (or multiple) system LB-1 constitutes a perfect example of such a complex multi-D problem. Thus far, the LB-1 system has been indirectly investigated by 1D stellar-atmosphere codes and by spectral disentangling techniques, yielding differing conclusions about the nature of the system (e.g., a B-star and black-hole binary with an accretion disc around the black hole or a stripped-star and Be-star binary system have been proposed). Aims. To improve our understanding of the LB-1 system, we directly modelled the phase-dependent Hα line profiles of this system. To this end, we developed and present a multi-purpose binary-object spectral-synthesis code in 3D (BOSS-3D). Methods. BOSS-3D calculates synthetic line profiles for a given state of the circumstellar material. The standard pz-geometry commonly used for single stars is extended by defining individual coordinate systems for each involved object and by accounting for the appropriate coordinate transformations. The code is then applied to the LB-1 system, considering two main hypotheses, a binary containing a stripped star and Be star, or a B star and a black hole with a disc. Results. Comparing these two scenarios, neither model can reproduce the detailed phase-dependent shape of the Hα line profiles. A satisfactory match with the observations, however, is obtained by invoking a disc around the primary object in addition to the Be-star disc or the black-hole accretion disc. Conclusions. The developed code can be used to model synthetic line profiles for a wide variety of binary systems, ranging from transit spectra of planetary atmospheres, to post-asymptotic giant branch binaries including circumstellar and circumbinary discs and massive-star binaries with stellar winds and disc systems. For the LB-1 system, our modelling provides strong evidence that each object in the system contains a disc-like structure.

Imprint of intrinsic ocean variability on decadal trends of regional sea level and ocean heat content using synthetic profiles

The global ocean is warming and has absorbed 90% of the Earth Energy Imbalance over 2010–2018 leading to global mean sea level rise. Both ocean heat content (OHC) and sea level trends show large regional deviations from their global means. Both quantities have been estimated from in-situ observations for years. However, in-situ profile coverage is spatially uneven, leading to uncertainties when assessing both OHC and sea level trends, especially at regional scale. Recently, a new possible driver of regional sea level and OHC trends has been highlighted using eddy-permitting ensemble ocean simulations over multiple decades: non-linear ocean processes produce chaotic fluctuations, which yield random contributions to regional decadal OHC and sea level trends. In-situ measurements capture a combination of the atmospherically-forced response and this intrinsic ocean variability. It is therefore important to understand the imprint of the chaotic ocean variability recorded by the in-situ measurement sampling in order to assess its impact and associated uncertainty on regional budgets. A possible approach to investigate this problem is to use a set of synthetic in-situ-like profiles extracted from an ensemble of forced ocean simulations started from different states and integrated with the same atmospheric forcing. Comparisons between the original ensemble outputs and the remapped, subsampled, in-situ-like profiles elucidate the contribution of chaotic ocean variability to OHC and regional sea level trends. Our results show that intrinsic variability may be large in eddy-active regions in the gridded model outputs, and remains substantial when using the in-situ sampling-based estimates. Using the latter, the same result is also found on large scales, for which atmospheric forcing has been identified as the main driver. Our results suggest accounting for this intrinsic ocean variability when assessing regional OHC and sea level trend budgets on decadal time scales.

Variations of the Plasma Environment Revealed by the Evolution of the Supra-arcade Fan in the 2017 September 10 Flare

Based on observations from the Interface Region Imaging Spectrograph and Hinode, we analyze the thermodynamic evolution of the supra-arcade fan (SAF) in the 2017 September 10 flare. The SAF presents discontinuous characters during the rising process, indicating a nonuniform process of magnetic reconnection in the solar eruption. The intensity peaks of the high-temperature spectral lines (Fe xxi 1354.08 Å, Fe xxiii 263.76 Å, and Fe xxiv 255.10 Å) basically correspond to the valley of the Doppler velocity and Doppler width. The temperature and density increase spatially at the upper boundary of the SAF. These results indicate that a compressed interface may exist in the SAF, where the plasma environment shows remarkable changes in density, temperature, and turbulence. In view of the fact that the height of the SAF is close to the hard X-ray source, we conclude that the interface could be related to termination shocks (TSs), taking into account the synthetic spectral profiles obtained from numerical experiments. In turn, the variations of the spectral profiles might be useful tools for identifying TSs from EUV spectral observations.

Millisecond pulsar kicks cause difficulties in explaining the Galactic Centre gamma-ray excess

ABSTRACT The unexplained excess gamma-ray emission from the Milky Way’s Galactic Centre has puzzled astronomers for nearly a decade. Two theories strive to explain the origin of this excess: self-annihilating dark matter particles or an unresolved population of radio millisecond pulsars. We examine the plausibility of a pulsar origin for the GeV excess using N-body simulations. We simulated millisecond pulsars in a realistic dynamical environment: (i) pulsars were born from the known stellar mass components of our Galaxy; (ii) pulsars were given natal velocity kicks as empirically observed from two different studies (or, for comparison, without kicks); (iii) pulsars were evolved in a Galactic gravitational potential consistent with observations. Multiple populations of pulsars (with different velocity kicks) were simulated over 1 Gyr. With final spatial distributions of pulsars, we constructed synthetic gamma-ray surface brightness profiles. From comparisons with published Fermi-LAT surface brightness profiles, our pulsar simulations cannot reproduce the concentrated emission in the central degrees of the Bulge, though models without natal velocity kicks approach the data. We considered additive combinations of our (primordial MSP) simulations with models where pulsars are deposited from destroyed globular clusters in the Bulge, and a simple model for pulsars produced in the nuclear star cluster. We can reasonably reproduce the measured central gamma-ray surface brightness distribution of Horiuchi and collaborators using several combinations of these models, but we cannot reproduce the measured distribution of Di Mauro with any combination of models. Our fits provide constraints on potential pathways to explain the gamma-ray excess using MSPs.

Institutions of Higher Education in the Russian Federation: Budgetary and Private Impact of Education at the University Level

This article considers at the university level the graduates’ income information, as well as budgetary and private cost estimates to determine budgetary and private impact of education using the calculation of internal rate of return. Since the graduates’ income information is available for only three-year period after the graduation, the synthetic profile of the graduates’ income during their lives is constructed according to the regional microdata. Results of the calculation show that the average impact of higher education is about 9 %, which is consistent with other estimates. In addition to list of universities indicating their impact, the article presents conclusions and recommendations, based on the analysis of the impact’s types and the correlation with other parameters, particularly with Unified State Examination scores for entry into higher education. The article’s value consists in demonstration of the possible approach for estimates, considering impact of investment in higher education at the university, faculty or department level. Researchers of the future can build on methodology and estimates, presented in this article, to obtain more accurate and reliable data on private impact of investment in higher education.

A modified Milne-Eddington approximation for a qualitative interpretation of chromospheric spectral lines

Context. The Milne-Eddington approximation provides an analytic and simple solution to the radiative transfer equation. It can be easily implemented in inversion codes used to fit spectro-polarimetric observations and infer average values of the magnetic field vector and the line-of-sight velocity of the solar plasma. However, in principle, it is restricted to spectral lines that are formed under local thermodynamic conditions, namely, photospheric and optically thin lines. Aims. We show that a simple modification to the Milne-Eddington approximation is sufficient to infer relevant physical parameters from spectral lines that deviate from local thermodynamic equilibrium, such as those typically observed in the solar chromosphere. Methods. We modified the Milne-Eddington approximation by including several exponential terms in the source function to reproduce the prototypical shape of chromospheric spectral lines. To check the validity of such an approximation, we first studied the influence of these new terms on the profile shape by means of the response functions. Then we tested the performance of an inversion code including the modification against the presence of noise. The approximation was also tested with realistic spectral lines generated with the RH numerical radiative transfer code. Finally, we confronted the code with synthetic profiles generated from magneto-hydrodynamic simulations carried out with the Bifrost code. For the various tests, we focused on the vector magnetic field and the line-of-sight velocity. We compared our results with the weak-field approximation and center of gravity technique as well. Results. The response function corresponding to the new terms in the source function have no trade-offs with the response to the different components of the magnetic field vector and line-of-sight velocity. This allows us to perform a robust inference of the physical parameters from the interpretation of spectral line shapes. The strategy has been successfully applied to synthetic chromospheric Stokes profiles generated with both standard models and realistic magnetohydrodynamic (MHD) simulations. The magnetic field vector and velocity can be successfully recovered with the modified Milne-Eddington approximation. Conclusions. Milne-Eddington model atmospheres that include exponential terms are not new to the solar community but have been overlooked for quite some time. We show that our modification to the Milne-Eddington approximation succeeds in reproducing the profile shape of two chromospheric spectral lines, namely, the Mg I b2 line and the Ca II at 854.2 nm. The results obtained with this approach are in good agreement with the results obtained from the weak field approximation (for magnetic field) and the center of gravity (for velocity). However, the Milne-Eddington approximation possesses a great advantage over classical methods since it is not limited to weak magnetic fields or to a restricted range of velocities.

Improved ozone simulation in East Asia via assimilating observations from the first geostationary air-quality monitoring satellite: Insights from an Observing System Simulation Experiment

The Geostationary Environment Monitoring Spectrometer (GEMS) is the world's first air quality instrument in the geostationary (GEO) orbit to monitor trace gases and aerosols at an unprecedented spatial and temporal resolution over East Asia, shedding light on the gradually alarming ozone pollution contrary to declining precursor emissions in this region. Here we use synthetic GEMS ozone profiles through the Observing System Simulation Experiment (OSSE) for evaluating the benefit of GEMS hourly measurements on chemical data simulation based on a Kalman filter technique. Assimilating synthetic GEMS data improves surface ozone simulation as its root-mean-square error (RMSE) is reduced by 7.2–19.2% over major urban areas in East Asia, along with a more accurate (6.3–29.2%) capturing of high-ozone events. The assimilation also better represents ozone vertical distributions in the middle to upper troposphere and better captures stratospheric intrusion events, with an RMSE reduction of 18.2–49.2% between 200 and 300 hPa. Our OSSE study offers a valuable reference for future ozone simulations, especially when massive observations become available in the coming era of GEO satellites.

Modelling charge profiles of electric vehicles based on charges data

Background: The correct design of electric vehicle (EV) charging infrastructures is of fundamental importance to maximize the benefits for users and infrastructure managers. In addition, the analysis and management of recharges can help evaluate integration with auxiliary systems, such as renewable energy resources and storage systems. EV charging data analysis can highlight informative behaviours and patterns for charging infrastructure planning and management. Methods: We present the analysis of two datasets about the recorded energy and duration required to charge EVs in the cities of Barcelona (Spain) and Turku (Finland). In particular, we investigated hourly, daily and seasonal patterns in charge duration and energy delivered. Simulated scenarios for the power request at charging stations (CSs) were obtained using statistical parameters of the Barcelona dataset and non-parametric distributions of the arrivals. Monte Carlo simulations were used to test different scenarios of users’ influx at the CSs, and determine the optimal size of an integrated renewable energy system (RES). Results: This study highlighted the difference between fast and slow charging users’ habits by analysing the occupancy at the charging stations. Aside from the charge duration, which was shorter for fast charges, distinct features emerged in the hourly distribution of the requests depending on whether slow or fast charges are considered. The distributions were different in the two analysed datasets. The investigation of CS power fluxes showed that results for the investment on a RES could substantially vary when considering synthetic input load profiles obtained with different approaches. The influence of incentives on the initial RES cost were investigated. Conclusions: The novelty of this work lies in testing the impact of different approach to design synthetic profiles in the determination of the optimal size of a photovoltaic (PV) system installed at a charging infrastructure, using the economic criterion of the net present value (NPV).

Transverse kink oscillations of inhomogeneous prominence threads: Numerical analysis and Hα forward modelling

Context. Prominence threads are very long and thin flux tubes that are partially filled with cold plasma. Observations have shown that transverse oscillations are frequent in these solar structures. The observations are usually interpreted as the fundamental kink mode, while the detection of the first harmonic remains elusive. Aims. The properties of oscillations in threads are greatly affected by the density distribution along the flux tube. Here, we aim to study how the density inhomogeneities in the longitudinal and radial directions modify the periods and damping times of kink oscillations and how this effect would be reflected in the observations. Methods. We solved the ideal magnetohydrodynamics equations using two different methods: (a) performing 3D numerical simulations and (b) solving a 2D generalised eigenvalue problem. We studied the dependence of the periods, damping times, and amplitudes of transverse kink oscillations on the ratio between the densities at the centre and at the ends of the tube, and also on the average density. We applied forward modelling to our 3D simulations to compute synthetic Hα profiles. Results. We confirm that the ratio of the period of the fundamental oscillation mode to the period of the first harmonic increases as the ratio of the central density to the footpoint density is increased, or as the averaged density of the tube is decreased. We find that the damping times due to resonant absorption decrease as the central-to-footpoint density ratio increases. Contrary to the case of longitudinally homogeneous tubes, we find that the damping-time-to-period ratio also increases as the density ratio is increased or the average density is reduced. We present snapshots and time-distance diagrams of the emission in the Hα line. Conclusions. The results presented here have implications for the field of prominence seismology. While the Hα emission can be used to detect the fundamental mode, the first harmonic is barely detectable in Hα. This may explain the lack of detections of the first harmonic. A combination of different spectral lines is required to obtain information about the period ratio and to use it to infer physical properties of the threads.