Ghost Structure Research Articles

Laser directed energy deposition remanufacturing of LPBF-processed TA15 parts: Hybrid process interface induced microstructure inheritance and mechanical performance

The laser additive hybrid manufacturing technology, which combines the precision of Laser Powder Bed Fusion (LPBF) and the flexibility of Laser Directed Energy Deposition (LDED), provides an effective solution for efficient forming and remanufacturing of large, complex components. The bonding zone (BZ) between LPBF and LDED forming regions is crucial for the final component performance. This study utilized LDED to remanufacture annealed LPBF substrates and investigated the microstructure and mechanical properties of TA15 alloy remanufactured parts. Results shows that a gradient microstructure forms at the bonding zone (BZ), where the bottom region exhibits a mixed structure including transitional β phase (βt), lamellar α and secondary α phase (αs). The top region shows a "ghost structure" of fine needle-like α phases. The mechanical property matched the microstructure well, as the hardness in the upper BZ reaches up to 463 MPa, whereas the LFZ exhibits the lowest hardness at 401 MPa. As the angle between the LDED region edge and tensile direction increases, the tensile strength first increases and then stabilizes, while elongation increases initially and then decreases. At a tilt angle of 60°, the strength peaks at 1098 MPa; at a 30° angle, the elongation reaches a maximum of 10.336%. All samples fracture at the LPBF zone, indicating that the formation of fine lamellar α phases in the BZ contributes to its higher strength compared to LPBF substrate and LDED deposition zones.

A Method for Detecting the Death State of Caged Broilers Based on Improved Yolov5

HighlightsRapid and accurate identification and detection of mortality in high-level caged broilers.Apply the state-of-the-art single-stage object detection model Yolov5 as the experimental infrastructure.Modify and improve the network structure, reduce the calculation amount of model parameters, and make the model easier to deploy.The data of dead broilers in different regions can also be quickly and accurately identified and detected, with excellent generalization.Abstract. In an unmanned broiler base, the automatic identification of the death state of broilers in a complex cage environment can effectively improve picking efficiency and reduce its negative impact. An improved Yolov5 object detection method is proposed in this study to rapidly and accurately detect the presence of dead broilers in caged structures. The Yolov5 model within the CSPDarknet53 framework is constructed, and the Yolov5 model is experimentally pruned to reduce the number of convolution kernels. The Ghost structure and the Involution structure are combined with the Yolov5 backbone network to effectively reduce the number of parameters and computations with a negligible loss of accuracy, making it easier to deploy applications. The detection accuracy of the model can reach 99.2%. The number of parameters is reduced from 7.05M to 0.31M, and the amount of calculation is reduced from 16.3 to 0.3. It can be seen that the improved Yolov5 network is practical and suitable for high-precision real-time detection and recognition of the death state of broilers in a caged structure. Keywords: Keywords.,Computer vision, Dead chicken detection, Machine vision, Yolov5.

Uncovering the hierarchical clusters in the heat-affected zone of an electron beam welded α/β titanium alloy joint

Using high-resolution transmission Kikuchi diffraction (TKD) and transmission electron microscopy (TEM), we examined the hierarchical clusters that form in situ in the heat-affected zone (HAZ), which are commonly referred to as “ghost” structures, of bimodal titanium alloy Ti-5Al-2Sn-2Zr-4Mo-4Cr (wt%, TC17). The ghost structures are enriched with Al elements but poor in Mo and Cr compared to the surrounding β matrix. TKD results show that the ghost structure in middle-HAZ mainly consists of αL laths with a high-angle grain boundary, which exhibits the classic Burgers orientation relationship (BOR) with the host matrix, while it encircles the αP grains in far-HAZ. And the ghost structure is evidenced to form via incomplete martensitic transformation. TEM results further confirm that the ghost structure is composed of αL and tiny βL laths with BOR, with the former being enriched with Al and poor with Cr and Mo, while the latter is the opposite. Interestingly, two αL variant clusters with a check-mark morphology are frequently observed viewed along [0001]αL//[110]βL directions, which are dominated by the crystallographic and geometrical relationships between α and β phases. Based on the microstructural characterization, it is hypothesized that the ghost structure is transformed from the initial αP phase, due to the coupling effect of high thermal stress (which induces the formation of a large number of dislocations) and element diffusion caused by sudden temperature increase and plunge cooling in the HAZ during the welding process.

SAR Image Aircraft Target Recognition Based on Improved YOLOv5

Synthetic aperture radar (SAR) is an active ground-surveillance radar system, which can observe targets regardless of time and weather. Passenger aircrafts are important targets for SAR, as it is of great importance for accurately recognizing the type of aircraft. SAR can provide dynamic monitoring of aircraft flights in civil aviation, which is helpful for the efficient management of airports. Due to the unique imaging characteristics of SAR, traditional target-detection algorithms have poor generalization ability, low detection accuracy, and a cumbersome recognition process. Target detection in high-resolution SAR images based on deep-learning methods is currently a major research hotspot. You Only Look Once v5 (YOLOv5) has the problems of missed detection and false alarms. In this study, we propose an improved version of YOLOv5. A multiscale feature adaptive fusion module is proposed to adaptively assign different weights to each scale of the feature layers, which can extract richer semantic and textural information. The SIOU loss function is proposed to replace the original CIOU loss function to speed up the convergence of the algorithm. The improved Ghost structure is proposed to optimize the YOLOv5 network to decrease the parameters of the model and the amount of computation. A coordinate attention (CA) module is incorporated into the backbone section to help extract useful information. The experimental results demonstrate that the improved YOLOv5 performs better in terms of detection without affecting calculation speed. The mean average precision (mAP) value of the improved YOLOv5 increased by 5.8% compared with the original YOLOv5.

Internal tensile properties of characteristic zones in the electron beam weldment of TC17 titanium alloy

The internal tensile deformation of the individual base metal zone (BM), heat-affected zone (HAZ), and fusion zone (FZ) in a titanium alloy (Ti–5Al–2Sn–2r–4Mo–4Cr, wt.%) electron beam welding (EBW) joint is investigated. The ultimate strength of BM with a bimodal microstructure is 1047.5 MPa, and the elongation to fracture is 9.8%. HAZ is distinguished by the formation of a ghost structure with a hierarchical cluster structure within the initial αP grains, while the embedded αs laths dissolve in the matrix and relatively coarsening β grains are generated. During tension, the ghost structures strongly inhibit and deflect slip initiation and extension in the relatively coarsening β matrix. The competitive balance between strengthening from the ghost structure and weakening from the coarsening matrix dominates the mechanical properties of the HAZ, which then induces a hybrid fracture. The needle-shaped thermal martensite that formed during EBW causes the FZ to fail prematurely. The microstructural evolution of HAZ and FZ decreases their mechanical properties. This research may shed some light on the mechanical enhancement of titanium alloys by utilizing the multiple αL laths precipitated within the initial αP structure associated with the bimodal matrix.

Starch retrogradation in potato cells: Structure and in vitro digestion paradigm

The consumption of foods with intact cellular structure is recognized to lower the glycemic index. Studies have focused on the gelatinization and digestibility of starch in intact cells. However, the effects of intact cells on starch retrogradation and digestibility are still unclear. Mild acid and alkali soaking were used to isolate intact potato cells and hydrothermal treatment (73 °C for 30 min) followed by retrogradation (4 °C for 0–15 days). The retrogradation period of 0–15 days increased the crystallinity and enthalpy change, while decreased the digestion rate and extent in potato cell and starch ghost samples. Furthermore, the existence of cell wall (potato cell) lowered the starch digestion rate and extent than potato starch ghost. It was concluded that the ghost structure is the main factor that controls the starch retrogradation, whereas the intact cell wall structure provides the barrier for starch digestion and protects the ghost structure.

Microstructure and mechanical properties of forging-additive hybrid manufactured Ti–6Al–4V alloys

The forging-additive hybrid manufacturing technology has combined the advantages of traditional manufacturing in efficiency and cost with those of additive manufacturing in flexibility and rapid prototyping, thus can provide an effective solution for the efficient forming of large and complex components. In this kind of manufacturing technology, the heat affected zone (HAZ, also called as bonding zone) between the wrought substrate zone (WSZ) and the laser deposition zone (LDZ) is the key to the properties of final components. In this study, the powder-feeding laser additive manufacturing technology was employed to deposit bulk samples on a wrought Ti–6Al–4V substrate containing bimodal microstructures. The microstructures and mechanical properties of hybrid manufactured Ti–6Al–4V alloys were studied with emphasis on the HAZ. The results show that, due to the different history of thermal, a graded microstructure was formed from the bottom to the top of HAZ. The bimodal microstructure at the bottom-HAZ gradually transformed to a mixed structure contained equiaxed α, lamellar α, and a large number of secondary α in the middle-HAZ, while the top-HAZ exhibits Widmanstätten structures consisting lamellar α and the so-called ghost structures due to the insufficient diffusion of alloying elements. The measurement of mechanical properties shows that, the sample with bonding zones presents higher tensile strength and yield strength, but lower elongation than those without bonding zones (WSZ or LDZ). The fracture positions of all samples with bonding zones are in WSZ and far away from HAZ, indicating a better strength of bonding zone than that of the wrought substrate and the laser deposition part due to the formation of secondary α and fine lamellar α in HAZ.

“Ghost structures” in alkaline fen microrelief as a consequence of Late Glacial periglacial activity in chalklands – a case study from the Chełm Hills (East Poland)

On the basis of high-resolution LiDAR data, collected at the surface of alkaline fens in the Chełm Hills area (Lublin chalkland, East Poland), structures deviating from the natural paludification processes related to the development of fens (“ghost structures”) were identified. At each of the sites analysed, field verification by means of drillhole cores indicates an indirect relationship between the modern topography of the peatlands and the morphology of their substratum, related to periglacial processes. Three categories of periglacial structure were recognized in the chalk bedrock: (1) solifluction sheets, lobes and terraces; (2) pingo-type structures (ramparted depressions, lithalsas); and (3) relict cryogenic mounds. A conceptual model of the development of slope and peatland relief in the Lublin chalkland during the Late Glacial and Holocene was prepared on the basis of the results obtained. The results indicate the role of the periglacially transformed chalk substratum in the development of alkaline fens in the chalklands, which rarely was considered in previous studies.

A ghost structure finite difference method for a fractional FitzHugh-Nagumo monodomain model on moving irregular domain

In this paper, a ghost structure (GS) finite difference method is proposed to simulate the fractional FitzHugh-Nagumo (FHN) monodomain model on a moving irregular computational domain. In the GS formulation the moving irregular domain is converted into a fixed regular domain (called ghost structure), and the transmembrane potential is described in the Eulerian coordinates, while the membrane dynamics are described in the Lagrangian coordinates. The transformation between the Lagrangian variables and the Eulerian variables is achieved by an integral transformation which involves a delta function. The GS formulation allows to compute the transmembrane potential in a fixed regular domain using the finite difference method on a Cartesian grid, which has a huge advantage for approximating domain-dependent fractional derivatives. To overcome the difficulty caused by running time-consuming loops to compute the transformation between the Eulerian and Lagrangian variables, two fast algorithms are proposed to compute the transformation. Extensive numerical tests are provided to demonstrate the effectiveness and robustness of the proposed GS finite difference method for solving the fractional FHN monodomain model. We first numerically study the transmembrane potential propagation in both healthy hearts and hearts with arrhythmia by simulating the model in the transverse of a ventricle. We then study the transmembrane potential propagation during the pumping process, which requires to simulate the model in the moving longitudinal section of a ventricle. Our numerical results show that the change of spatial derivatives can affect the propagation velocity and the width of the transmembrane potential wave, and for a heart with arrhythmia, the transmembrane potential begins to enter cyclically the region where cardiomyocytes have been excited and then stimulates cardiomyocytes to contract again.

General procedure of gauge fixings and ghosts

We revisit the general procedure of gauge fixings and ghosts based on BRST invariance principle. It is shown that when this is applied to the higher-derivative gauge fixings, it gives the correct structure of gauge fixings and ghosts including “third ghost”, previously derived at one-loop level. This procedure is solely based on the symmetry principle and is valid at full order.

Microstructure and long-term corrosion of archaeological iron alloy artefacts

The smithing skills of craftsmen in the western Mediterranean during the early Iron Age can be determined by studying the microstructure of oxidised iron items. While some ghost structures have already been identified in dense corrosion products, their formation has not always been explained. Four objects from southern France were analysed using optical microscopy, X-ray diffraction, micro-Raman spectroscopy and field-emission scanning electron microscopy coupled with energy dispersive spectroscopy and electron backscatter diffraction. The role of microstructure, grain boundaries, cracks, species diffusion through oxides in soil corrosion and the initial microstructure are discussed. An additional parallel degradation mechanism (graphitisation) was experimentally revealed.

U/Th dating and open system behavior: implications for travertines based on the study of Süttő (Hungary) and Ballik (Turkey) sites

Reliable dating is essential in order to put palaeoclimatological, palaeoenvironmental and archeological information from continental carbonates in the correct time frame. This study evaluates U/Th dating of travertines based on two case studies, i.e., in the Ballik (Denizli, SW Turkey) and Suttő (N Hungary) areas. Previous petrographic, mineralogical and elemental characterization of the travertines enabled sampling of, purely calcitic, micrite or spar dominant, zones that are non-, or solely weak, cathodoluminescent. Despite adapted sampling and detrital thorium corrections, U/Th ages of the Ballik and the Suttő travertines are inconsistent with their stratigraphic position. Based on the observation of wavy extinction affecting micritic fabrics and ghost structures, the studied travertines behaved as an open system for uranium after deposition through recrystallisation. Their U/Th ages, consequently, can only be considered as minimum ages. The Ballik travertines precipitated earlier than 0.55-1.31 Ma ago, when late-stage cementation along fractures and in cavities took place, and form the oldest travertines deposited in the Denizli basin. The formation of the Suttő travertine area started at the earliest around 2.5 Ma with precipitation of the Cukor travertine. With some short interruptions, active travertine formation in the area took place maximally until 120 ka. The decreasing ages of the Suttő travertines towards the Danube, prove the complex nature of travertines both during deposition as well as during diagenesis, which leads to anomalies with regard to the law of superposition. The diagenetic susceptibility of continental carbonate deposits poses problems in terms of accurate and precise dating. U/Th dating of the intrinsically heterogeneous fabrics of travertines and tufa, as presently applied, should be ceased. Travertines and tufa up to ~100 ka might be the exception due to the limited extent of recrystallisation. Sparite cements and veins can be dated more accurately but, even with multiple samples from the same study site and inclusion of coeval samples, give only minimum ages for the whole deposits. To better constrain the time frame of the whole bodies, results from independent dating methods and from the surrounding deposits are necessary. In addition, it is important to keep in mind that the open-system behavior of continental carbonates has implications for diagenetic, palaeoenvironmental and palaeoclimatological studies based on geochemical proxies.

Simulation of action potential propagation based on the ghost structure method

In this paper, a ghost structure (GS) method is proposed to simulate the monodomain model in irregular computational domains using finite difference without regenerating body-fitted grids. In order to verify the validity of the GS method, it is first used to solve the Fitzhugh-Nagumo monodomain model in rectangular and circular regions at different states (the stationary and moving states). Then, the GS method is used to simulate the propagation of the action potential (AP) in transverse and longitudinal sections of a healthy human heart, and with left bundle branch block (LBBB). Finally, we analyze the AP and calcium concentration under healthy and LBBB conditions. Our numerical results show that the GS method can accurately simulate AP propagation with different computational domains either stationary or moving, and we also find that LBBB will cause the left ventricle to contract later than the right ventricle, which in turn affects synchronized contraction of the two ventricles.

Bimetric, conformal supergravity and its superstring embedding

We discuss the connection between Weyl2 supergravity and superstrings and further discuss holography between 4-dimensional, mathcal{N} = 4 superconformal Weyl2 supergravity and mathcal{N} = 8, higher spin-four theory on AdS5. The Weyl2 plus Einstein supergravity theory is a special kind of a bimetric gravity theory and consists of a massless graviton multiplet plus an additional massive spin-two supermultiplet. Here, we argue that the additional spin-two field and its superpartners originate from massive excitations in the open string sector; just like the mathcal{N} = 4 super Yang-Mills gauge fields, they are localized on the world volume of D3-branes. The ghost structure of the Weyl action should be considered as an artifact of the truncation of the infinitely many higher derivative terms underlying the massive spin 2 action. In field theory, mathcal{N} = 4 Weyl2 supergravity exhibits superconformal invariance in the limit of vanishing Planck mass. In string theory the additional spin-two fields become massless in the tensionless limit. Therefore low string scale scenarios with large extra dimensions provide (almost) superconformal field theories with almost massless open string spin-two fields. The full mathcal{N} = 4 scalar potential including the Yang-Mills matter multiplets is presented and the supersymmetric vacua of Einstein Supergravity are shown, as expected, to be vacua of massive Weyl supergravity. Other vacua are expected to exist which are not vacua of Einstein supergravity. Finally, we identify certain spin-four operators on the 4-dimensional boundary theory that could be the holographic duals of spin-four fields in the bulk.

Reevaluating early iron-working skills in the Southern Levant through microstructure analysis

The question of whether improved technological skills of Iron Age smiths, such as carburization and quenching, were behind the significant transition to utilitarian use of iron in the eastern Mediterranean has been long debated, with the answer relying on the analyses of a few exceptionally well-preserved objects from Israel and Cyprus. In order to systematically examine this question, 59 iron objects from several major Iron Age settlements in Israel were sampled for metallographic analysis. First and foremost, it is shown that none of the analyzed objects were preserved in metallic form and that only in rare cases, small islands of metallic iron were preserved. Objects with full preservation of metal, heavily relied upon in past discussions, are therefore the exception and not the rule.Using relics (“ghost structures”) of the original metallic microstructure, pearlite and cementite were observed in an overwhelming majority of the samples, indicating that almost all of the objects were made of steel. A wide variety of carbon concentrations was estimated, reflecting a range of compositions from low-carbon hypoeutectoid to high-carbon and hypereutectoid steels. Since no clear correlation between object type and steel quality was observed, we conclude that steeling was, in fact, a spontaneous and non-deliberate result of the smelting process, rather than a deliberate systematic act of carburization. In addition, martensitic structures, indicative of quenching, were not identified, suggesting that quenching was not routinely performed and that iron was unlikely to have been superior to bronze at this time. It thus appears that the iron-working skills of the Iron Age smiths cannot be used as a factor that can explain the advent of iron in the Southern Levant nor as a reason for the dramatic increase in iron production during the 10th–9th centuries BCE.

Low Florida coral calcification rates in the Plio-Pleistocene

Abstract. In geological outcrops and drill cores from reef frameworks, the skeletons of scleractinian corals are usually leached and more or less completely transformed into sparry calcite because the highly porous skeletons formed of metastable aragonite (CaCO3) undergo rapid diagenetic alteration. Upon alteration, ghost structures of the distinct annual growth bands often allow for reconstructions of annual extension ( = growth) rates, but information on skeletal density needed for reconstructions of calcification rates is invariably lost. This report presents the bulk density, extension rates and calcification rates of fossil reef corals which underwent minor diagenetic alteration only. The corals derive from unlithified shallow water carbonates of the Florida platform (south-eastern USA), which formed during four interglacial sea level highstands dated approximately 3.2, 2.9, 1.8, and 1.2 Ma in the mid-Pliocene to early Pleistocene. With regard to the preservation, the coral skeletons display smooth growth surfaces with minor volumes of marine aragonite cement within intra-skeletal porosity. Within the skeletal structures, voids are commonly present along centres of calcification which lack secondary cements. Mean extension rates were 0.44 ± 0.19 cm yr−1 (range 0.16 to 0.86 cm yr−1), mean bulk density was 0.96 ± 0.36 g cm−3 (range 0.55 to 1.83 g cm−3) and calcification rates ranged from 0.18 to 0.82 g cm−2 yr−1 (mean 0.38 ± 0.16 g cm−2 yr−1), values which are 50 % of modern shallow-water reef corals. To understand the possible mechanisms behind these low calcification rates, we compared the fossil calcification rates with those of modern zooxanthellate corals (z corals) from the Western Atlantic (WA) and Indo-Pacific calibrated against sea surface temperature (SST). In the fossil data, we found a widely analogous relationship with SST in z corals from the WA, i.e. density increases and extension rate decreases with increasing SST, but over a significantly larger temperature window during the Plio-Pleistocene. With regard to the environment of coral growth, stable isotope proxy data from the fossil corals and the overall structure of the ancient shallow marine communities are consistent with a well-mixed, open marine environment similar to the present-day Florida Reef Tract, but variably affected by intermittent upwelling. Upwelling along the platform may explain low rates of reef coral calcification and inorganic cementation, but is too localised to account also for low extension rates of Pliocene z corals throughout the tropical WA region. Low aragonite saturation on a more global scale in response to rapid glacial–interglacial CO2 cyclicity is also a potential factor, but Plio-Pleistocene atmospheric pCO2 is generally believed to have been broadly similar to the present day. Heat stress related to globally high interglacial SST only episodically moderated by intermittent upwelling affecting the Florida platform seems to be another likely reason for low calcification rates. From these observations we suggest some present coral reef systems to be endangered from future ocean warming.

Cyclotella hinziae sp. nov. - a small Cyclotella (Bacillariophyceae) from subalpine lake Schliersee (Bavaria, Germany)

A small Cyclotella species (Thalassiosiraceae) from a subalpine lake Schliersee (Bavaria, Germany) is described. The species has characteristic valve morphology different from this of the other similar taxa. It differs from them especially with the presence of radially arranged ghost structures in the valve central part and with the presence and low number of transversal trabeculae inside the alveolus - maximally 6 in 1 μm. The valve morphology and ultrastructure of this taxon is described and its new name, Cyclotella hinziae, is proposed. Its valve morphology is compared and discussed with this of other similar taxa.

Ghost Structures, Pasting, Rheological and Textural Properties between Mesona Blumes Gum and Various Starches

AbstractIn this study, the ghost structures of potato starch granule gelatinization in the presence and absence of Mesona Blumes gum (MBG) at different temperatures and time points were studied. Our results indicated that ghost structures could form merely after the amylose was completely leached from granules. In addition, MBG could prevent amylose from leaching outside the granules, and thus extend ghost structure existence in aqueous solution. Furthermore, the interactions among eight kinds of starches and MBG were assessed by Brabender parameters. It was concluded that rice, wheat, pea and corn starches could be significantly influenced by MBG (P < 0.05), then followed by mung bean and sweet potato starch, whereas the effects of tapioca and potato starch could be insignificant (P > 0.05). Textural measurement illustrated that MBG/rice starch gel was the hardest among all samples in this study. Rheological properties of rice starch and various hydrocolloids were evaluated at 25C by frequency sweep from 1 to 10 Hz with a constant strain 1%. It was shown that rice starch and MBG could also form the strongest gel.Practical ApplicationsTo understand the interaction between MBG and different starches from various sources, ghost structures, Brabender curves, and textural and rheological properties were investigated in this paper. Ghost structure indicated that gels between MBG and starch might be constituted by collapsed starch granule, MBG and swollen amylose. Brabender curves showed that MBG could affect rice starch gelatinization significantly (P < 0.05). Moreover, the results of textural studies also demonstrated that MBG/rice starch gels formed the hardest gel. In addition, the results obtained from rheological properties between various hydrocolloids and rice starch suggested that the strongest MBG/rice starch gel occurred. Therefore, gels formed by MBG and rice starch might be potentially used as a novel filler or thickener in food industry.

Petrologic and Structural Features of Basement Rocks of Parts of Mukuru Area, Southeastern Nigeria

Field investigations in the western part of Mukuru area indicate intense structural imprints and high HT/HP metamorphism, and some magmatism. The rock units in the area include migmatitic gneisses, granulites, amphibolites, schists, charnockites, epidiorites and granites. The charnockites which are common in the shear zone and boundary areas appear to mark the end of magmatism. However, relicts of magmatic rocks mapped at Ubong Community in the study area suggest earlier magmatism. The metamorphic rocks are strongly deformed in a N-S to NE-SW direction with ghost structures, pinch and swell structures, ptygmatic veins, showing evidence of extensional tectonics. No visible contact relationship between the migmatitic gneisses and schists was observed. Diagnostic metamorphic structures like fine banding/layering of alternating dark- and light-coloured layers are conspicuous in gneisses and some amphibolites while schistosity and deep weathering are present in schists. The geodynamic features prevalent in Mukuru area are deformation and metamorphism. They indicate a possible petrogenetic link to southern Obudu Plateau in the north, western Cameroon in the east than Bansara in the west.

The gauge structure of generalised diffeomorphisms

We investigate the generalised diffeomorphisms in M-theory, which are gauge transformations unifying diffeomorphisms and tensor gauge transformations. After giving an E n(n)-covariant description of the gauge transformations and their commutators, we show that the gauge algebra is infinitely reducible, i.e., the tower of ghosts for ghosts is infinite. The Jacobiator of generalised diffeomorphisms gives such a reducibility transformation. We give a concrete description of the ghost structure, and demonstrate that the infinite sums give the correct (regularised) number of degrees of freedom. The ghost towers belong to the sequences of representations previously observed appearing in tensor hierarchies and Borcherds algebras. All calculations rely on the section condition, which we reformulate as a linear condition on the cotangent directions. The analysis holds for n < 8. At n = 8, where the dual gravity field becomes relevant, the natural guess for the gauge parameter and its reducibility still yields the correct counting of gauge parameters.